President Joseph Kabila is in the lead in the Democratic Republic of Congo's election with 46% of the vote, official results show. With more than two-thirds of votes counted, his closest challenger, Etienne Tshisekedi, trails on 36%, the election commission says. Full results are due later on Tuesday and there is tension after the opposition alleged fraud. Some 3,000 people fled the capital, Kinshasa, at the weekend. Last Monday's polls were the second since the 1998-2003 war officially ended, following the loss of some four million lives but armed groups continue to operate in eastern parts of the country. The BBC's Thomas Fessy in Kinshasa says Mr Tshisekedi's supporters insist that he has won and are unlikely to accept defeat in polls marred by allegations of rigging, including pre-marked ballots. Mr Kabila's constitutional mandate to rule ends on Tuesday and the opposition said it would not recognise his authority thereafter, our reporter says. Police fired tear gas at opposition supporters in the capital on Monday, and gunfire rang out in a city in West Kasai province, both seen as opposition strongholds, after the government shut down a television and radio broadcaster, Reuters news agency reports. There was more violence on Monday night outside Mr Tshisekedi's home in Kinshasa and the headquarters of his Union for Democracy and Social Progress (UDPS) party, our reporter says. 'Conflict risk alert' Mr Tshisekedi's supporters staged demonstrations in South Africa, the main regional power, and Belgium, the former colonial power, on Monday to demand that Mr Tshisekedi be declared the winner. The protesters tried to storm the DR Congo embassy in Pretoria, forcing police to fire tear gas, the AFP news agency reports. There were also protests in Johannesburg, where five people were reportedly arrested. The protesters accused South Africa's President Jacob Zuma of helping to organise fraudulent elections in DR Congo and said he should stay out of DR Congo's affairs. In Brussels, police fired water cannons to disperse protesters. On Thursday, the UDPS declared Mr Tshisekedi the winner and called for arrangements to be made for a transfer of power. Mr Tshisekedi, 78, campaigned for democracy under former ruler Mobutu Sese Seko but it is the first time he has contested elections. He boycotted the 2006 election, claiming it had been rigged in advance. Several thousand residents of Kinshasa crossed the River Congo to neighbouring Congo-Brazzaville at the weekend as fear grew that violence could escalate, correspondents say. Many foreign nationals have also fled the country, they say. The International Crisis Group has put DR Congo on its "conflict risk alert" list. Last week, four other opposition candidates - including Vital Kamerhe, a former ally of Mr Kabila - called for the polls to be annulled, alleging they had been marred by widespread rigging and violence. Observers from the African Union (AU), the Southern African Development Community (SADC) and three other groups have said the polls had been successful and called on all sides to show restraint. The government warned that it would not tolerate further conflict. "We cannot let chaos prevail. If the situation becomes too chaotic for the police, we will definitely call for the army to come and help," Kikaya Bin Karubi, DR Congo's ambassador to the UK and a top official in Mr Kabila's camp, is quoted by Reuters news agency as saying. Guards loyal to Mr Kabila shot opposition protesters, killing 14, ahead of the election, Human Rights Watch said - claims dismissed by the government. HRW said at least four more people were killed during the poll. The election was marred by widespread logistical problems, as well as the violence, and polling in some areas was extended until Thursday to allow voting material to be delivered. DR Congo is two-thirds the size of Western Europe but has hardly any road or rail links between its major cities, so the UN peacekeeping mission distributed some election equipment by helicopter. The 2006 election was marred by weeks of street battles led by supporters of the losing candidate, Jean-Pierre Bemba. He is now on trial at the International Criminal Court for alleged war crimes committed in Central African Republic.