WASHINGTON: US senators have urged Secretary of State Hillary Clinton and Defense Secretary Robert Gates to make sure Pakistan is doing its utmost to battle extremists before disbursing more US security aid.

The lawmakers, all Democrats, wrote Clinton and Gates a letter Tuesday in the wake of the raid in which elite US commandos found and killed Al-Qaeda chief Osama bin Laden in a Pakistani military town not far from the country's capital.

“We recognize the strategic importance of Pakistan,” wrote the group, which include Senate Intelligence Committee Chairwoman Dianne Feinstein and Senate Finance Committee Chairman Max Baucus.

“However, we cannot overlook the logical conclusion of recent events, which is to question whether the Pakistani security establishment is ardently working to prevent terrorist groups from operating on Pakistani soil,” they said.

The senators called for reviewing Pakistan's efforts to end its support for extremist groups, prevent Al-Qaeda, the Taliban and others from operating on Pakistani soil, and bolster its counter-terrorism and anti money-laundering laws.

“We believe that conducting this assessment will be crucial for the Congress to determine whether to provide the full range of security assistance,” they said in the letter.

Pakistan received a total of $2.7 billion dollars in aid and reimbursements from Washington in fiscal year 2010, which ended on October 1, making it the third-largest recipient of US aid after Afghanistan and Israel.

Finding bin Laden in a Pakistani military town “indicates, at a minimum, a lack of commitment by the Pakistani military to aggressive cooperation with the United States,” the senators said.

“This is particularly concerning as the Congress again considers increasing security assistance to Pakistan,” they said.