KINSHASA, Aug 10 - Results trickling in from Congo's historic election confirm a two-man race between the incumbent president and a former rebel leader but 10 days after the vote, experts caution the results are still tentative.

President Joseph Kabila is currently leading with just over 46 percent of the 1.6 million votes so far counted from Democratic Republic of Congo's first free election in more than 40 years. Jean-Pierre Bemba trails with about 24 percent.

Despite observers' warnings not to project results from the partial figures, speculation is mounting over whether Kabila will win the majority needed to avoid a run-off in late October.

"It is going to be very close either way," a Western diplomat told Reuters. "Two rounds would make it seem more legitimate but there is nothing we can do about that."

The partial figures reveal an east-west divide in the vast mineral-rich former Belgian colony, which analysts have warned could herald a legitimacy crisis for a new president.

Kabila is winning easily in his native Swahili-speaking east while Bemba is sweeping his western homeland, where Lingala is spoken. The remaining votes are scattered among 30 candidates.

Congo's July 30th elections were the culmination of a peace process meant to end a 1998-2003 war, which sparked a humanitarian crisis that has killed more than 4 million people, more than any conflict since World War Two.

But battling the circulation of fake results and chaotic scenes at counting centres, Congo's electoral commission has announced figures from just 25 of 169 voting constituencies across a nation the size of Western Europe.

"These are still very tentative results," said one U.N. official. "We shouldn't start making projections until 30 or 40 percent of the vote has been counted."

KABILA POPULAR In the east, many voters backed Kabila for what they saw as his role in ending the war, which badly ravaged the area. In former Rwandan-backed rebel stronghold of Goma, in the eastern province of North Kivu, Kabila won 88 percent of votes cast.

In the west, Bemba appealed to voters who oppose a president from the east who doesn't speak their language. In several constituencies in his native Equateur province, Bemba won well over 80 percent.

Harvard-trained doctor Oscar Kashala heads the rest of the candidates but trails the two front-runners by a long way.

The international community, which has paid more than $450 million for the polls, is trying to diffuse tensions fuelled by complaints of fraud by some candidates.

International observers are encouraging people to check the results being published are the same as the ones they witnessed at polling stations on voting day.

"This is a positive step that the electoral commission is publishing the results," said Colin Stewart, regional co-director of the Carter Centre. "It is a very transparent measure and should put to rest any doubts people had."

Many fear a second round would be preceded by violent campaigning, playing on ethnic divisions. Analysts also warn Bemba's supporters are unlikely to accept a first-round victory by Kabila.

Tensions are particularly high in the capital where many Congolese say foreign powers want to see Kabila elected.

"If Bemba does not win, or even get into the second round, this place will burn. We voted for him and we want him president," said Jacques, an unemployed youth in his 20s.