(Adds latest results, paragraphs 2-3)
By Katrina Manson and Christo Johnson
FREETOWN, Aug 20 (Reuters) - The two main opposition candidates in Sierra Leone’s presidential polls said on Monday they were joining forces in a bid to beat the country’s vice president, Solomon Berewa, in a runoff expected next month.
With votes counted from 93 percent of polling stations after the first round a week ago, main opposition candidate Ernest Bai Koroma of the All People’s Congress (APC) party is leading with 44 percent of the vote. Berewa is on 38 percent.
With neither close to the 55 percent needed to win outright in the first round, a run-off looks inevitable.
Charles Margai of the People’s Movement for Democratic Change (PMDC), running third with 14 percent and seen as a potential kingmaker, pledged to back Koroma in the second round.
"We will support the APC in the case of a runoff, under the leadership of Ernest Bai Koroma," Margai told Reuters in a room packed with senior party officials after hours of talks.
"I think it will be an overwhelming win. I think the second round would be for the APC even without our support, but we want to ensure that we have a say in the government of this country."
The elections are the first in the former British colony since United Nations peacekeepers left two years ago and are seen as a test of its recovery from a 1991-2002 civil war.
Outgoing President Ahmad Tejan Kabbah is stepping down as required by the constitution, but Berewa, his vice-president, is the candidate for his Sierra Leone People’s Party (SLPP).
"Margai’s decision to ally with the APC has not hampered my party’s hope to win the presidential election if there is a second round," Berewa told Reuters.
"It is the democratic right for the PMDC candidate to make his choice as to whatever party he would want his party to ally with," he said in an interview.
Many ordinary Sierra Leoneans say they are tired of the SLPP’s failure to tackle corruption, which analysts and diplomats say means vital aid is being squandered. Sierra Leone is the highest per capita recipient of British aid.
Koroma, a 53-year-old former insurance executive, said the support of the PMDC, founded by Margai in 2006 when he split from the SLPP after failing to win the presidential nomination, would be a great help.
"It will make a lot of difference," Koroma said. "It will provide a united platform for this country ... A good number of (Margai’s) supporters believe in him and will rely on his judgement."
But not all of those who backed Margai in the first round — many of them former SLPP supporters — are expected to heed his call to back Koroma next month, meaning the runoff is expected to be a closely fought contest.