By Dino Mahtani

LONDON (Reuters) - Democratic Republic of Congo has awarded lucrative forestry concessions to a company controlled by a Lebanese businessman who also runs a firm subject to sanctions by the United States as a front for Hezbollah.

The 2011 concessions issued by Congo's environment ministry to the Trans-M company, seen by Reuters, could complicate Washington's efforts to curb what it says are the Lebanese militant movement's growing business activities in Africa.

The concessions cover 25-year leases for hundreds of thousands of hectares of rainforest in the central African country, the world's second forest "lung" after the Amazon. The concessions are capable of generating hundreds of millions of dollars in revenues over 25 years, if fully exploited, forestry experts say.

Trans-M is controlled by businessman Ahmed Tajideen (whose name is also given as Tajeddine in U.S. Treasury documents). He also runs another company, Congo Futur, which the U.S. government says is a front for Hezbollah. Congo Futur cites sawmilling as one of its businesses.

The U.S. Treasury Department put Congo Futur under targeted sanctions in 2010, saying the firm was part of a network of businesses ultimately controlled by Tajideen's three brothers, Kassim, Husayn and Ali, and that this generated "millions of dollars in funding" for Hezbollah.

The sanctions aim to block U.S. dollar transfers linked to the trio, part of wider U.S. efforts to counter what Washington sees as increasing business activity in Africa by Hezbollah, which it calls "among the most dangerous terrorist groups in the world". Hezbollah has denied U.S. accusations that it is linked to money-laundering and the international narcotics trade.

Ahmed Tajideen, who is not subject to U.S. Treasury sanctions, says his brothers have no share of Congo Futur or Trans-M and that the companies are neither directly related to each other nor act as front companies for Hezbollah.

"I am the majority shareholder of both companies," Tajideen told Reuters earlier this month.

"I created both companies independently of each other", he said. "My brothers have nothing to do with the companies".

EMBARRASSING FOR KABILA

But leaked U.S. diplomatic cables produced in 2000 quote Ahmed Tajideen as saying Congo Futur established Trans-M, which is also described as a "subsidiary" of Congo Futur on the website of Congo's official investment authority, ANAPI.

"The question for the Congolese government is whether they really want to continue doing business with a company that is linked to a terrorist organization?" said a U.S. official who monitors Congo, but asked not to be named.

John Sullivan, a U.S. Treasury spokesman, told Reuters that if Trans-M was majority owned by Congo Futur, it would face sanctions. He would not comment on the immediate status of Ahmed Tajideen or Trans-M.

"Treasury does not comment on possible enforcement actions or designations," he said.

The Trans-M forestry concessions are an embarrassment for the government of President Joseph Kabila, who was returned to office in last year's troubled presidential elections that were criticized by the United States as "seriously flawed".

Seraphim Ngwej, a senior advisor to president Kabila, told Reuters the U.S. government had not officially communicated any allegations about the concessions to Congo's government.

He said he would be willing to assist. "But there must be proof," Ngwej said.

Leopold Kalala Ndjibu-Kalema, a senior legal adviser to Congo's environment ministry, said in an official statement that there is "no concrete proof" that Trans-M is involved in Hezbollah activities and insisted its concessions had nothing to do with Congo Futur.

But a European Union-funded forestry publication in 2011 refers to Congo Futur as the "parent company" of Trans-M. Employees and a business partner of Congo Futur contacted by Reuters have also stated Trans-M is a "subsidiary" of Congo Futur and is owned by all the Tajideen brothers.

"WEAK STATES"

U.S. officials are concerned that Congo, whose location in the heart of Africa makes it important for the continent's stability, may become a safe haven for Hezbollah financiers looking to take advantage of weak financial regulation in the lawless and commodity rich central African giant.

"We do have major concerns about all weak states, and especially places like Congo," said one U.S. official who asked not to be named. "The attention here in Washington is pretty high," he added.

U.S. authorities last year put the spotlight on Hezbollah's Africa-based activities by unveiling a Drug Enforcement Administration (DEA) probe alleging the Iranian-backed group was involved in money laundering activities in West Africa linked to the narcotics and second hand car trade.

The Tajideen family has operated real estate, diamond export, supermarket and food processing businesses across Angola, Gambia and Sierra Leone and Congo for many years, the U.S. Treasury says.

West and Central Africa host significant and long-established Lebanese diaspora communities. But U.S. interest in the Tajideen family sharpened in 2003 when Belgian police raided the Antwerp offices of a company managed by Kassim Tajideen and accused it of "large scale tax fraud, money laundering and trade in diamonds of doubtful origin". No charges were brought in Belgium.

The U.S. Treasury made Kassim Tajideen subject to sanctions in 2009 and in 2010 also sanctioned Husayn Tajideen and Ali Tajideen, who it says was once a Hezbollah commander in Lebanon. The Treasury says Husayn and Ali are amongst Hezbollah's "top financiers in Africa".

A Hezbollah official declined to comment on the U.S. allegations. When the Treasury sanctioned some of the family's companies in 2010, U.S. citizens were barred from doing business with them. But some of the companies continued to operate freely in their host countries, including Congo Futur.

Israel has also expressed concern about what it says are growing Hezbollah financial interests in Africa.

Ron Prosor, Israel's ambassador to the United Nations, told the Security Council last month that he was particularly concerned that West Africa had become a "hub" for Hezbollah. But he did not refer to central Africa or Congo.

Powerful Israeli businessmen still retain good relations with president Kabila, notably Dan Gertler, a wealthy diamond merchant who controls numerous mining and other interests in Congo, many managed via offshore companies.

(Additional reporting by Jonny Hogg in Kinshasa; Editing by Pascal Fletcher)