The United States has condemned Sunday's return of controversial Afghan warlord Abdul Rashid Dostum from exile in Turkey.

The U.S. Embassy in Kabul said Washington has expressed concern to the Afghan government about the warlord's prospective role in today's Afghanistan and particularly during presidential elections, scheduled for Thursday.

Dostum's return is seen as a move to strengthen electoral support for President Hamid Karzai, who seeks re-election.  Before his exile, Dostum was appointed chief of staff of the armed forces by President Karzai. 

Dostum had been living in exile since last year, when the government released him from house arrest for fighting with a rival.  Rights workers have accused his forces of killing up to 2,000 Taliban prisoners early in the Afghan war, but he denies wrongdoing.

Earlier, Mr. Karzai, former finance minister Ashraf Ghani and former planning minister Ramazan Bashardost held a nationally broadcast debate.  It was the first time a standing president participated in such a debate. 

But one of the top contenders, former foreign minister Abdullah Abdullah, decided not to attend. 

Also Sunday, government officials responsible for security in Afghanistan said they cannot ensure complete security before and during the elections, but that they are doing their best to protect voters. 

Defense Minister General Abdul Rahim Wardak announced a unilateral cease-fire on election day, saying Afghan forces will only be on the defensive to prevent violence.

In violence Sunday, three more British soldiers were killed in southern Helmand province, bringing Britain's death toll in Afghanistan to 204.  Two other British soldiers died Saturday.

Some information for this report was provided by  AP and Reuters.