WASHINGTON (Reuters) - The Treasury Department put two people that it alleged have ties to militant Islamist groups active in Afghanistan on a blacklist on Thursday and banned American citizens from any dealings with them.

The Treasury's Office of Foreign Assets Control said Bakht Gul was a communications official for the al Qaeda-linked Haqqani Network, accused by the United States of involvement in attacks in Afghanistan, and that Abdul Baqi Bari was a money launderer for the Taliban.

Treasury said Bari funneled funds to support al Qaeda and that Osama Bin Laden, the al Qaeda leader killed in a U.S. raid on his hideout in Pakistan last year, had given Bari and an associate $500,000 to buy a factory in 2002.

It said Gul relayed reports from commanders in Afghanistan to the Haqqani Network, which is based along the Afghanistan-Pakistan border, and had coordinated movements of weapons and insurgents.

Besides forbidding Americans from doing business with the two, Treasury said that any assets that they were found to be holding in the United States will be blocked.

(Reporting By Glenn Somerville; editing by Mohammad Zargham)