UPDATE 2-Liberia president extends lead, short of vote majority
* Half of votes counted so far, election body says
* Johnson-Sirleaf at 45 pct, top rival Tubman at 29.5 pct (Adds quotes, details)
MONROVIA, Oct 14 (Reuters) - President Ellen Johnson-Sirleaf has extended her lead in Liberia's election but remains short of the outright majority required for a first-round win, according to the latest batch of results announced by the election commission on Friday.
The newly named Nobel peace laureate now leads with 45.4 percent of the votes in the West African state's second presidential vote since its civil war, up from 44.5 percent in results on Thursday and ahead of closest rival Winston Tubman, now on 29.5 percent, according to the results.
"A little more than half the ballots have been counted, we're just past the halfway mark," NEC Chairman James Fromayah told a press conference, adding that full results were likely to be ready before an Oct. 26 deadline.
"We will definitely finish ahead of schedule."
The election is Liberia's first locally-organised poll since an on-and-off 1989-2003 conflict, and if smooth could pave the way for billions of dollars in mining and oil investment.
A run-off will take place in early November if no candidate secures more than 50 percent of the vote.
Former rebel leader Prince Johnson was in third place with 11.4 percent of the nearly 600,000 valid votes counted, the NEC said, most of which came from his bastion of minerals-rich Nimba County -- Liberia's second most populous of 15 counties.
Johnson told Reuters in an interview on Friday that he would welcome a "kingmaker" role if there were a run-off between Johnson-Sirleaf and Tubman, adding that he would negotiate for key government posts for his party and seek to change the minerals revenue management law.
Turnout at the polling stations counted so far has averaged 70.2 percent, the NEC said. Liberia has about 1.8 million registered voters.
The counting from Montserrado, Liberia's biggest county that includes the capital, Monrovia, has been coming in slowly, drawing criticism from Tubman's CDC party, which claims it as one of their strongholds. The CDC said it has also filed a formal complaint with the NEC over allegations that electoral officials secretly opened at least three sealed ballot boxes.
Johnson-Sirleaf went into the vote as the favourite but Tubman, whose running mate is former soccer star George Weah, has sought to tap into simmering frustrations, especially among Liberian youth.
Although Liberia has seen increasing investment and has managed to convince donors to waive billions of dollars in debt, many residents say progress has been too slow and complain of a lack of basic services, high food prices, rampant crime and corruption. (Writing by David Lewis; Editing by Mark Heinrich)