Afghanistan's presidential elections will be delayed four months until Aug. 20 to allow extra international forces enough time to bolster security, the election commission said Thursday.

Lawmakers were expected to make provisions to avoid a power vacuum after President Hamid Karzai's five-year term officially expires May 22, said Azizullah Lodin, the head of the Independent Election Commission.

However, some legislators decried the delay as unconstitutional and warned of a crisis of power, saying there is no legal way to extend the president's term.

Afghanistan's constitution says the election should be held by late April, but Lodin told reporters in Kabul that the security situation was not strong enough for polls to occur that soon.

He said the commission had agreed to wait for additional international forces, who will arrive in the coming months, because their presence would improve security during the vote. U.S. military leaders have said up to 30,000 new American forces could be sent to Afghanistan in 2009. Thousands of those troops are being sent to the south, Afghanistan's most violent region.

"Without security, there can be no election," Lodin said.

The delay to the vote — which will likely give Karzai several more months in office — is allowed under an article in the electoral law that addresses a lack of security or logistical preparations for a peaceful vote, Lodin said.

The August ballot is a compromise between a desire by Karzai's office to postpone the vote until the fall and calls from lawmakers for elections to be held in the spring, he said.

But some parliamentarians said the electoral commission needs to find a way to hold a vote within the timeline set out in the constitution. Under the charter, elections are supposed to be held 30 to 60 days before the expiry of incumbent president's term.

Habeba Danish, a parliamentarian from Takhar province in the north, said security problems are not enough of a reason to hold back the vote.

"The Afghan government and the international community were not able to establish security over the last seven years. If they delay the election even as long as a year or so, they still won't have enough security in all parts of the country," Danish said.

In a reminder of ongoing violence, the U.S. military said coalition forces killed four armed militants during a strike on the compound of Taliban operative in southern Zabul province.

Wednesday's fighting in Tarnak Wa Jaldak district started when the militants fired on the international troops, the military said in a statement.

Gul Pacha Mujedi, a lawmaker from southeastern Paktia province, meanwhile, said the delay violates Afghanistan's constitution. He said that there has been no agreement between Parliament and the electoral commission and that the commission does not have the authority to act alone.

Lodin said the constitution's description of the handover of power suggests the president should stay in office until after elections take place.

But Abdul Hadi Safi, a lawmaker from northern Kapisa province, argued that the constitution is very clear that the president's term ends on May 22 and said he could not see another interpretation of the clause.

Several Afghan politicians have said they will run against Karzai, but none of the candidates who have declared so far is expected to present Karzai with a strong challenge.

Election officials have been holding voter registration drives around the country the last several months. But worries have arisen that Afghans in the country's most violent districts will not be able to take part in the vote.

Lodin said logistical and financial issues also prevent the poll from being held in the spring.

"We have had security problems, budgetary problems and technical problems," he said.

Lodin said it would be nearly impossible to distribute ballots in Afghanistan's mountainous regions during winter and early spring because of the extreme weather conditions. In addition, the electoral commission is still far short of the $223 million required to hold the presidential and provincial council votes, Lodin said.

NATO Secretary-General Jaap de Hoop Scheffer said he wasn't concerned that the delay would hamper work by the bloc's forces in Afghanistan.

"It will give us time to work on what I consider to be one of the most important priorities for NATO and (NATO's International Security Assistance Force) this year — that is election support," de Hoop Scheffer said. NATO troops are currently working to help with voter registration in Afghanistan.