An influential U.S. lawmaker on Tuesday proposed withholding aid to Uganda after the African nation's president signed a controversial new measure imposing life prison sentences for homosexuals.

"I am deeply concerned by the decision of President (Yoweri) Museveni of Uganda to sign into law the anti-homosexuality bill," Senator Patrick Leahy, the most senior member of the chamber and chairman of the Senate Judiciary Committee, said in a statement.

"Much of US assistance to Uganda is for the people of Uganda, including those in the Ugandan LGBT (lesbian, gay, bisexual and transgender) community whose human rights are being so tragically violated," he added.

"But we need to closely review all U.S. assistance to Uganda, including through the World Bank and other multilateral organizations."

Washington is among Uganda's largest international donors.

The State Department said that in current fiscal year some $485 million in bilateral assistance had been provided to Uganda with most of the funds going towards health programs, as well as education, food security and military training.

The State Department has signalled it is looking at a range of options to respond to the law, while White House spokesman Jay Carney said "we are undertaking a review of our relationship with Uganda in light of this decision."

State Department spokeswoman Jen Psaki meanwhile hit out a Ugandan newspaper for "an aggressive invasion of privacy" after it listed 200 people it accused of being gay with their photographs.

The report highlighted concerns that enactment the law "creates a climate where people could face discrimination, could even face violence," Psaki told reporters.

Leahy chairs the appropriations subcommittee on State Department and foreign operations, and he has several options at his disposal, including inserting language in a 2015 aid bill that puts conditions on U.S. assistance to Uganda.

Some lawmakers argued against cutting off aid.

"Africa is a continent in peril. The problems in Uganda with AIDS, and, you know, kids starving -- do we deny economic aid to the developing world in Africa, which could be an ally, over an issue like this?" asked Republican Senator Lindsey Graham.

"I'm not so sure that's the right answer."

Fellow Senate Republican James Inhofe, who has traveled to Africa dozens of times and has strong connections to Uganda, said he was "offended" by the anti-gay law but suggested blocking aid would be counterproductive.

"We can all express ourselves on how we oppose" the new law, he told AFP. "But if we start making that the predicate for what our policy is going to be on all issues, I think that's probably the wrong way to do it."

Washington has praised Uganda for successfully tackling HIV/AIDS. The Kampala government has prioritized abstinence and faith in addition to condom use, and the UN recorded a plunge in Uganda's HIV prevalence, from 18.5 percent in 1992 to five percent in 2000.