NATO's chief warned Tuesday that, despite a disputed election, Afghanistan must sign a security pact on a post-combat international training mission by September, or there will be "severe" problems for the Western alliance.

Anders Fogh Rasmussen said after meeting President Barack Obama that allegations of poll fraud were a "grave concern" and he hoped an audit could produce a credible outcome so the new Afghan president could sign security agreements before the NATO summit in Wales in early September.

"If there is no clarification of this process before the NATO summit in September, it is hard to see how the security agreements could be signed before the summit," the NATO Secretary General said.

"In that case, we would be faced with severe problems as regards planning for a training mission after 2014."

Rasmussen stressed that Afghanistan's signature on a Bilateral Security Agreement (BSA) with the United States and a companion security deal with NATO nations were a "pre-requisite" for a force that will initially number around 10,000 men and then taper down gradually over the next several years.

The Obama administration has previously warned that there will no troops left behind to train Afghan forces if the deal, which outgoing Afghan President Hamid Karzai has refused to sign, is not completed.

Both candidates in Afghanistan's disputed presidential election, Abdullah Abdullah and Ashraf Ghani, have told Washington they will endorse the deal.

But it is unclear whether prolonged wrangling over the result of second round presidential polls will delay the Afghan inauguration, set for August 2, and the signing of the deal laying down the legal, political and military scope of the future NATO force.

The remaining 50,000 international combat troops are due to leave Afghanistan by the end of the year, and foreign forces will no longer patrol Afghan towns or cities.

Afghan suicide attack kills 16, including 4 Czech soldiers
Kabul (AFP) July 08, 2014 - A Taliban suicide bomber killed 16 people including 10 civilians and four Czech soldiers in an attack in eastern Afghanistan Tuesday, officials said, as foreign troops wind down their war against the insurgents.

Czech chief of staff Petr Pavel told reporters in Prague that the bomber was in a crowd of Afghans talking to soldiers who were investigating rocket attacks against Bagram airbase, a major US military facility nearby.

The attack, which was claimed by the Taliban, comes as Afghanistan is mired in political crisis, with a bitter row raging over allegations of fraud in the presidential runoff election.

Waheed Sediqqi, spokesman for the governor of Parwan province, told AFP that ten civilians and two policemen were killed in the attack as well as the four soldiers.

The insurgents said 15 US special forces soldiers were killed. They routinely make exaggerated claims after such attacks.

About 250 Czech soldiers serve among the 50,000 US-led NATO troops still deployed in Afghanistan.

NATO's combat mission will wrap up at the end of this year, with 10,000 US troops staying into next year if the new president signs a security deal with Washington.

About 3,450 coalition troops have been killed in Afghanistan since operations began in 2001 when the Taliban regime was ousted from power.

US Secretary of State John Kerry warned Tuesday that any attempt to seize power in the election crisis would cost the country its international aid.

Initial results released on Monday showed former World Bank economist Ashraf Ghani had won the election, but a spokesman for his poll rival Abdullah Abdullah rejected the outcome as "a coup against the will of the people".

Fraud allegations immediately stoked concerns of instability after the figures showed Ghani collected 56.4 percent of the run-off vote against ex-foreign minister Abdullah's 43.5 percent.