KABUL: New partial results in Afghanistan's presidential election released Sunday show candidate Abdullah Abdullah is still the front-runner, though a runoff election looks likely.

The winner will replace Hamid Karzai, the only president the country has known since the 2001 US-led invasion ousted the Taliban, and will oversee a tumultuous period during which the US and Nato forces are expected to withdraw most of their troops from the country.

Both Abdullah, and his closest competitor, Ashraf Ghani Ahmadzai, have promised a fresh start with the West and have vowed to sign a security pact with the US that Karzai refused to sign.

The chairman of Afghanistan's Independent Election Commission, Ahmad Yousuf Nouristani, announced the results Sunday.

They represent about half of the estimated 7 million ballots cast in the April 5 poll, though varying levels of votes have been counted in the country's 54 provinces.

Abdullah, Karzai's top rival in the country's last election, has 44 per cent of the vote tallied. Ghani, a former finance minister and World Bank official, received 33.2 per cent of the vote.

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Abdullah, speaking in an interview with The Associated Press shortly after the results were announced, said he still thinks it's possible for him to avoid a runoff altogether but said he was ready for a second round.

“For us, we will accept the outcome of a fair and transparent process. Anything short of that will be problematic,” he said.

“It's important that the process is a free and fair one. That is important. Then if it goes to the second round in accordance to the rule of law, we are ready for that as well. At this stage, we believe that another round might not be needed.”

The results were a slight improvement for Abdullah from the first results announced on April 13, but so far still not enough for him to avoid a runoff with Ghani. Final results are scheduled to be released on May 14, and officials have cautioned that results could change before then.

Karzai was constitutionally barred from running for a third term. Abdullah was the runner-up to Karzai during the 2009 vote which was marred by widespread allegations of fraud. He has drawn on his strong following among ethnic Tajiks in Afghanistan's north but is perceived to be weak among the country's largest ethnic group – the Pashtuns – even though he's half-Pashtun.

This race is a clear improvement for Ghani, who received just under 3 per cent of the vote in 2009.

Zalmai Rassoul, a former foreign minister widely considered as Karzai's pick, has 10.4 per cent of the vote.