SANAA/ADEN Local security officials said up to 20 soldiers were killed when Yemen's air force mistakenly bombed a military site in the south of the country on Sunday, but government and military sources denied the reports.
"We are not sure of the number yet but some 18 or 20 soldiers were killed, the plane bombed a small military site in Abyan. They meant to target an al Qaeda hideout," a security official told Reuters by telephone from the flashpoint Abyan province.
A defense ministry source denied "the false news that Yemeni soldiers were killed in an accidental Yemeni plane strike."
Yemen's army is fighting to regain territory lost to suspected al Qaeda operatives during months of political upheaval that have weakened central government control over parts of the country, notably Abyan.
A military source in the area said there was some confusion over what happened in several sites of fighting in Abyan on Sunday.
He said there had been several air strikes and al Qaeda attacks, and said the soldiers' deaths were not caused by a botched strike but a militant ambush on an army site.
The government said its troops had pushed Islamist fighters out of Abyan's capital Zinjibar last month, but clashes continue to flare there.
Local officials said nine soldiers were killed when militants ambushed government forces in the east of the city on Sunday. Another 23 were injured.
Separately, but also in Zinjibar, four more soldiers died in combat with gunmen and 15 militants were killed in air strikes on Sunday, local officials and residents said.
Since popular protests against President Ali Abdullah Saleh paralysed impoverished Yemen earlier this year, international powers have feared growing lawlessness might embolden al Qaeda's local wing and imperil shipping routes via the Red Sea.
FEAR OF CIVIL WAR
Saleh's opponents accuse him of exaggerating the threat of al Qaeda and even encouraging militancy to scare Saudi Arabia and the United States into backing him.
Diplomats said Western countries are hoping to step up pressure on Saleh to resign with a proposed United Nations Security Council resolution, as frustration grows over fruitless power transition talks.
"The international community has decided we need to up the pressure now," one senior western diplomat in Sanaa said.
"No decision has been taken yet over what type of resolution we might try ... But we do need to move beyond statements now."
Saleh had been in Saudi Arabia since June recovering from an attempt on his life. His surprise comeback coincided with a burst of bloodshed in the capital when a months-old uneasy stalemate gave way to a military showdown between pro- and anti-Saleh forces.
Violence has been sporadic since Saleh's return, but many Yemenis and analysts fear the country may eventually slide into an even deadlier confrontation, if not civil war.
There were clashes again in Sanaa on Sunday, with residents reporting gunfire near the base of top general Ali Mohsen, who defected from Saleh in March and threw his weight behind protests calling for an end to his 33-year rule.
Residents said men were digging trenches in front of the capital's presidential palace, raising concern they were preparing for more fighting.
"They've renewed the trench digging and they're building dirt mounts around the presidential palace," one resident said. "It started last night and even today they're still digging."
(Reporting by Mohammed Ghobari, Erika Solomon and Dhuyazen Mukhashaf; Writing by Isabel Coles; Editing by Sophie Hares)