Sri Lanka has offered to supply the U.N. with three Mi-24 attack helicopters and a pair of fix wing aircraft, a pledge that would help the U.N. meet a severe a shortfall in lethal combat equipment in places like Congo and Sudan and help protect civilians, U.N. based officials told Turtle Bay.

But the U.N. may not be able to accept them.

The Sri Lankan armed forces have come under scrutiny for allegedly committing mass atrocities during the final 2009 offensive against the country's separatists Tamil Tigers. A decision to accept the Sri Lankan offer would not only generate controversy but potentially trigger a U.S. review of Sri Lanka's human rights conduct.

Under the so-called Leahy law, written by Senator Patrick Leahy (D-Vermont)the State Department is required to vet the human rights records of foreign military contingents serving in U.N. peacekeeping missions, if there is reason to believe they may have been engaged in atrocities.

An independent panel, set up by U.N. Secretary General Ban Ki moon, concluded in April that there are "credible allegations" that Sri Lanka troops, as well as the separatist Liberation Tigers of Tamil Eelam, committed war crimes and crimes against humanity. More than 40,000 civilians may have died in the war, most of them victims of indiscriminate government shelling, according to the U.N. panel.

The Sri Lanka pledge appears calculated to improve Sri Lanka's relationship with the United Nations at a time when it is facing mounting U.N. pressure to hold alleged war criminals within the army's ranks accountable for crimes, according to U.N. officials. It would certainly be harder, they say, to criticize Colombo if the organization was dependent on its air force for vital assets in combat.

Peacekeepers from other countries, including Rwanda, have faced scrutiny over alleged rights abuses. The Rwanda government threatened to withdraw its peacekeeping force from Darfur, Sudan, after the U.N. moved to force out a Rwandan commander, General Karake Karenzi, who was allegedly involved in rights abuses in Rwanda and eastern Congo during the mid to late 1990s. The United States backed Karenzi, despite internal U.S. government concerns about his rights record.

Sri Lanka has participated in U.N. peacekeeping operations for more than 50 years, and it currently has more than 1,200 blue helmets serving in U.N. missions. In his September 2010 address to the U.N. General Assembly, Sri Lankan President Mahinda Rajapaska, defended Sri Lanka's conduct during the war while affirming Sri Lanka's "willingness to further enhance our support to the U.N. Peacekeeping Operations."

"Our armed forces and the police are today combat tested, with a capacity to carry out their duties in the most challenging conditions."