US gives Somalia about 40 tons of arms, ammunition

* U.S. details amount, type of weapons given to Somalia

* Arms provided after insurgents began offensive in May

WASHINGTON, June 26 (Reuters) - The U.S. government has provided about 40 tonnes of weapons and ammunition to Somalia's embattled government in the past six weeks to help it fight Islamist insurgents, a senior U.S. official said on Friday.

The official, who spoke on condition of anonymity, said the United States spent less than $10 million on what he described as small arms and ammunition as well as on payments to other nations to train Somali government forces.

While the State Department confirmed on Thursday that it was providing weaponry to the government, it had not previously provided details on the type, cost or amount.

The senior State Department official told reporters the United States began providing the arms soon after Somalia's al Shabaab insurgents began a major offensive against the fragile transitional federal government (TFG) in early May.

Al Shabaab, which is seen as a proxy for al Qaeda, controls most of south Somalia and all but a few blocks of the capital Mogadishu. The official said Washington feared that it could destabilize the region and turn Somalia into a safe haven for foreign Islamists and "global terrorists."

"We've shipped probably in the neighborhood of 40 tonnes worth of arms and munitions into Somalia," the official said. "We remain concerned about the prospects of an al Shabaab victory, and we want to do as much as we can to help the TFG."

The United States funded the purchase of arms for the Somali government and also asked the Ugandan and Burundian troops in the country to give the government weapons and then reimbursed them, the official said.

He said the United States also set aside money to pay the Ugandan and Burundian units to train government forces rather than having U.S. troops conduct the training.

When a moderate Islamist was elected president in January, there was hope he could end nearly two decades of bloodshed in Somalia by reconciling with hardliners who want to impose a strict version of Islamic law across the country.

But al Qaeda leader Osama bin Laden declared Somali President Sheikh Sharif Ahmed an enemy in an audiotape released in March, calling on the insurgents to topple the government and for Muslims around the world to join their fight.

The U.S. official said he had heard estimates of between 200 and 400 foreign fighters in Somalia but that his personal view was that the figure probably was less than 200.

(Reporting by Arshad Mohammed; Editing by Will Dunham)