President Hamid Karzai on Wednesday approved changes to the make-up of Afghanistan's electoral complaints watchdog, removing foreign UN representatives before presidential polls next year.

The changes approved by MPs in parliament on Monday will however keep in place the Election Complaints Commission (ECC) that was integral to unmasking massive fraud at the last presidential election in 2009.

The government ordered last year that the commission be replaced by a special tribunal appointed directly by Karzai, raising fears from rights groups that it would dilute efforts to clamp down on electoral abuse.

A 14-member commission of MPs on Monday approved keeping the ECC, but said it could no longer include two foreign UN representatives, bowing to a key Karzai demand.

Instead its five members will all be Afghans, still appointed by Karzai but from a short list put forward by a panel.

Afghanistan is due to hold a presidential election in April, at which Karzai will step down after serving a maximum two terms. Months later, the US-led NATO combat mission against the Taliban is due to end.

Donor nations have pressured the government to pass a series of election laws, seen as crucial to proving that the 12-year war and billions of dollars of aid money have not been in vain.

Karzai has not yet signed into law another bill approved by parliament in May that will determine how April's election is run.

But under Wednesday's amendments, MPs say the Election Complaints Commission will retain full power to throw out fraudulent votes, and it alone will have the power to announce the final election result.

Members will be nominated by a selection committee, which will include the speakers of both houses of parliament, the Supreme Court and human rights commission, and a civil society representative.

The same panel will also nominate the head of the Independent Election Commission, responsible for administering the polls and previously appointed directly by Karzai.

"I sign into effect the law for structures, authorities and duties of the elections commission and electoral complaints commission," Karzai announced in a decree.

"This decree has come into effect after being signed," he added.

In the 2009 presidential election, the Election Complaints Commission investigated thousands of complaints, mostly related to alleged ballot-rigging by Karzai supporters.

The watchdog ordered ballots from 210 polling stations to be disqualified in a probe that ultimately forced Karzai to accept a second-round run-off, which was abandoned when his opponent Abdullah Abdullah pulled out.

Local think tank, Afghanistan Analysis and Awareness, welcomed the reforms as an "important milestone in creating the right framework for ensuring democratic elections and strengthening the foundations of Afghanistan's young democracy".

But Martine van Bijlert, co-director of the rival Afghanistan Analysts Network, said that while the new nomination and selection procedure brings a sense of transparency it does not guarantee independence.

"The actual decision whom to appoint stays with the president," she told AFP by email.

"There are many ways to play any appointments system or to gain influence after people have been appointed -- not just by the president but by all parties."

The new system makes it harder for any party fully to control the appointment process, but "does not make the process immune from politicking or manipulation", she added.

It remains unclear who will run for president.

Among a long list of possible candidates are Qayum Karzai, the president's brother, Omar Daudzai, a former chief of staff, and warlord-turned-governor Atta Mohammad Noor.