By Feisal Omar and Abdi Sheikh
MOGADISHU (Reuters) - A debate on whether to sack Somalia's Prime Minister Abdiweli Sheikh Ahmed descended into chaos on Tuesday as his supporters blew whistles and shouted out slogans, forcing the parliamentary speaker to halt the session.
The no-confidence motion, which Washington had warned could deepen political turmoil, was backed by lawmakers loyal to President Hassan Sheikh Mohamud after the two men fell out over a cabinet reshuffle last month.
But politicians supporting the prime minister started beating on empty jugs, blowing on whistles and chanting "no motion" soon after the debate started, creating an almost deafening roar.
"Due to noise, we hereby close the session today. Let it be another day," parliament speaker Mohamed Sheikh Osman said after bringing the session to order about four hours later. He did not say when the debate would resume.
Western donors who have promised to help rebuild Somalia after two decades of conflict worry that the removal of a second prime minister in less than a year will weaken the government and leave it rudderless in its fight against Islamist rebels.
Ahmed's predecessor was also sacked by parliament after a similar row with Mohamud that paralysed the government for months last year.
Security around the bullet-scarred Somali capital was tightened before the debate, with increased police presence around parliament, said witnesses. Al Shabaab Islamist militants have attacked the building in the past.
Despite the arrangements, unidentified gunmen opened fire on a car carrying a lawmaker to parliament, killing the driver, according to another MP, Saaqo Aden.
The dispute between the two leaders erupted after Ahmed, an economist who has been in charge since December 2013, sidelined one of the president's key allies in a cabinet re-shuffle.
Lawmakers who put forward the no-confidence motion have accused the prime minister of doing a poor job and complained about the slow pace of change. The prime minister's office declined to comment on Tuesday.
Washington warned Somalia late on Monday about the dangers of holding the vote, saying it was "deeply concerned with political turmoil".
"Actions to put forward a parliamentary motion for a vote of no confidence in the prime minister do not serve the interests of the Somali people," said Jen Psaki, a U.S. State Department spokeswoman.
(Writing by Drazen Jorgic; Editing by Edith Honan and Andrew Heavens)