By Amena Bakr

UNITED NATIONS (Reuters) - International donors pledged another $1.46 billion in aid to Yemen on Thursday to help the poorest Arab country overcome financial challenges as it struggles to become a democracy against the backdrop of humanitarian and security crises.

Yemeni President Abd-Rabbu Mansour Hadi said the pledge will help Yemen avoid a civil war. Yemen was driven to the brink of bankruptcy by a year-long uprising that in February pushed long-time president Ali Abdullah Saleh from power and allowed al Qaeda to build its presence in lawless tribal regions.

The financial pledge was made during a Friends of Yemen meeting on the sidelines of the U.N. General Assembly in New York. In September, international donors had promised $6.4 billion in aid to Yemen during a meeting in Saudi Arabia.

The Friends of Yemen is a group of countries including the five permanent members of the U.N. Security Council - China, France, Russia, Britain and the United States - and Gulf states. No details were give on which countries were giving the $1.46 billion.

"Seventy percent of Yemen's problem is economic. The new pledge will help Yemen avoid a civil war which would be a local, regional and a global threat," Hadi told reporters after the meeting.

Restoring stability to Yemen has become an international priority given fears that al Qaeda linked militants could entrench themselves in the country, threaten world No. 1 oil exporter Saudi Arabia next door and important world shipping lanes.

The total pledge to date should be sufficient to meet budget shortfalls in the interim government's plan for economic reconstruction over the next 18 months, the World Bank said in a statement. "It will also be enough to support the new government in the immediate post-election period," it added.

Yemen and donor countries have set up a mutual accountability framework to ensure that aid is properly spent, and that countries deliver on their pledges.

Al Qaeda in the Arabian Peninsula (AQAP), which is al Qaeda's affiliate in Yemen, and other Sunni Muslim militant groups including Ansar al-Sharia gained ground last year during a popular uprising that forced out Saleh. The veteran autocratic president had been seen by the United States as reliable ally in containing militants.

Since replacing Saleh in February, Hadi has waged an army offensive to oust such groups from areas of Abyan province in south Yemen while the United States has stepped up a campaign of missile strikes on them.

British Foreign Secretary William Hague, who chaired the meeting with Saudi Arabia's Deputy Foreign Affairs Minister Prince Abdulaziz bin Abdullah, said Yemen had laid the foundations for a successful transition, but warned that more needed to be done.

"I welcome the steps taken so far to restructure the military and security, the successes in tackling AQAP in the south, and the creation of a preparatory committee for National Dialogue which is due to start in November," he said.

"It is vital that the pace of reform does not slip. Yemen remains in the grip of a serious humanitarian crisis, the economy needs to be rebuilt and the security threat is a cause of deep concern to all in the region."

(Additional reporting by John Irish; Editing by Will Dunham)