Afghan President Hamid Karzai offered government positions Thursday to his two top challengers in next week's presidential election, even as he insisted he had every expectation of a win.

At an election rally in Kabul Thursday, Karzai announced if he wins, "I will invite Dr. [Abdullah] Abdullah, I will invite Ashraf Ghani, give them food and tea and give them jobs, as I did last time."

While Karzai is the leading candidate in a field of about 40 contenders for the presidency, he is trailed by Abdullah and Ghani, his former foreign and finance ministers, respectively.

If no candidate wins 50 per cent of the vote on Aug. 20, the top two finishers will be forced into a run-off vote. That could open the possibility of a coalition uniting around a single candidate to try to defeat Karzai.

Ghani's campaign team said it rejected any pre-election deal with Karzai, while a spokesman for Abdullah's campaign said it would be the people who would decide who forms the government.

"Let's wait for next week's polling day and see the election results," Abdullah spokesman Sayyid Agha Hussain Fazel Sancharaki said.

Karzai easily won the country's first independent presidential election in 2004 on the first ballot. But since then, he has faced criticism for government corruption and a lack of everyday security. A recent United Nations report suggests there is evidence Karzai's officials have been using government resources to help swing the vote his way, but the allegations have not been proven.

Dr. Abdullah Abdullah has been gaining on Karzai in the polls in recent weeks, with thousands of Afghans turning out to see him speak in Kandahar recently. The 48-year-old former foreign minister has been able to raise doubts about Karzai's leadership, accusing him of being a dealmaker, not a leader, who has fallen prey to corruption.

CTV South Asian Bureau Chief Janis Mackey Frayer says it is criticism that is resonating with many voters who are disillusioned with progress made in the war-torn country and think foreign powers are in control.

"Even he is surprised by the level of support that he seems to be gathering," she told CTV's Canada AM by phone from Kabul on Thursday.

"He's running on a platform with a strong message of curbing corruption, building Afghan institutions, restoring Afghan confidence in the system that he says has been seriously compromised under the current government," she said.

But Abdullah, a doctor by profession who is fluent in English and French, lacks the vital support needed from many of the powerful regional warlords, which Karzai has.

With the election less than a week away, there are fears the Taliban could disrupt the vote. Almost daily, Taliban insurgents have been staging attacks on civilians and election members and warning people to stay away from polling centres on election day.

Karzai sought to ease the fears at a gathering of women supporters Thursday.

"Don't be worried about the threats, don't be worried at all. People are saying the election will be disturbed, there will be explosions. Let them try to disrupt the elections a hundred times, we will go to vote, even if there are a hundred explosions. We will go to vote for the success of the country," he told them.