WASHINGTON (CNN) -- The United States plans to shift about $230 million in aid to Pakistan from counterterrorism programs to upgrading the nation's aging F-16 fighter jets.

"We've shifted money to help the democratically elected government of Pakistan to fight a common foe, a common enemy that we have," said Gonzalo Gallegos, a State Department spokesman.

Pakistan is the largest recipient of payments from the Coalition Support Funds, which gives money to 27 partner countries help combat terrorism.

A senior State Department official told CNN "this has been developing for a while."

The new government is facing "a terrible financial crisis with food and fuel problems," the official said, and the Pakistani government "would rather tell its public they are spending their money on food and fuel," so it asked the United States to pay for the F-16 upgrades from the U.S. aid fund.

Last year, Congress mandated that $300 million in aid to Pakistan go toward fighting al Qaeda and the Taliban, partly by beefing up law enforcement and developing tribal areas of the country that are hostile to the United States.

Skeptical lawmakers worry that the F-16 upgrades will divert funding from crucial counterterrorism programs and could be more about helping Pakistan competing with its rival, India, than fighting terror.

Nita Lowey, chairwoman of a House subcommittee on foreign operations, said the request from Secretary of State Condoleezza Rice to reprogram the funding "raises serious concerns."

Lowey is asking for more information before signing off on the change.

"Congress provided these funds specifically for counterterrorism and law enforcement activities," Lowey said in a written statement.

"It is incumbent on the State Department and Pakistan to demonstrate clearly how these F-16s would be used to fight al Qaeda and the Taliban in order to get congressional support."

It is not the first time U.S. aid to Pakistan has come under scrutiny. In June, the Government Accountability Office and the House Committee on Foreign Affairs released a report that said the United States has not accurately tracked about $6 billion it gave to help the Pakistani government fight terrorism since 2001.

The country, which the Department of Defense considers a key ally in the war on terrorism because of its proximity to large swaths of ungoverned tribal land, has received $5.56 billion of $6.88 billion given out since the September 11 terrorist attacks.

U.S. and Pakistani officials claim that the F-16s are used to fly missions over regions near Pakistan's border with Afghanistan, where the Taliban are operating and al Qaeda leader Osama bin Laden is believed to be hiding.

The upgrades, which will bring the old fleet in line with new F-16s Pakistan recently purchased from the United States, will allow Pakistan's F-16 fleet to operate day and night missions and "effectively employ ground operations," Gallegos said.

The funds will be diverted from upgrades on other airplanes used for fighting terrorism, Gallegos said.

All About Pakistan • Al Qaeda • U.S. Department of State • The Taliban