By Joe Bavier KINSHASA, April 3 (Reuters) - No arrest warrant is pending for defeated presidential candidate Jean-Pierre Bemba, Congo's top prosecutor said Tuesday, as authorities bicker over his fate after clashes in Kinshasa last month. In the midst of the fighting between the army and Bemba's troops in late March, ministers said the ex-rebel leader was wanted on charges of treason for inciting the uprising, which diplomats believe may have killed up to 600 people. But Tshimanga Mukeba, Congo's state prosecutor, said an investigation was continuing into the role of Bemba, who is holed up inside the South African embassy while he waits to see if he can leave Democratic Republic of Congo. "If the government took a position, I wasn't associated," Mukeba told Reuters. "We are still in the stage of investigating." "When we finish, it's up to the senate to lift his immunity, and at that moment we'll be able to sign an international arrest warrant," he said. Bemba was elected as a senator earlier this year after losing a presidential runoff in October to incumbent Joseph Kabila. Bemba, who draws his support from the lingala-speaking west of the country including Kinshasa, has accused Kabila's supporters of fraud. Portugal has agreed to accept Bemba and his family, but only on a 90-day visa while he receives follow-up medical treatment for a leg he fractured in December. Portugal has yet to receive written approval from Congolese authorities allowing him to leave, although the Portuguese ambassador said a verbal agreement existed with the president of the parliament, Vital Kamerhe. Diplomats said the delay was due to disagreements in Kabila's administration over whether Bemba, who led a rebel faction in Congo's 1998-2003 war before serving as vice-president in a transition government, should be allowed to go abroad. JUDICIAL PROBLEM Kabila, who took office in December as Congo's first democratically elected leader in more than 40 years, told journalists last month that it was a judicial matter. A Kabila spokesperson said on Tuesday that the president was in the southeastern city of Lubumbashi. "Bemba is a judicial problem," said one government minister, who asked not to be identified. "This is not a government problem ... This has nothing to do with us." Mukeba, however, said the judicial investigation has no impact on whether Bemba will be permitted to leave. "This case doesn't concern the judiciary. We are not implicated. We have nothing to do with his departure," he said. Last month's fighting was the worst in Kinshasa since last year's polls, aimed at restoring peace to the mineral-rich central African state after the war in which 4 million people died, mainly through hunger and disease. Soldiers loyal to Kabila and Bemba had fought on several occasions in Kinshasa during last year's elections in clashes which killed at least 30 people and wounded many more.