KABUL (AFP) – A loud blast was heard Sunday in central Kabul, shaking residential buildings, two days ahead of a landmark international conference, a witness told AFP.

"A very loud explosion rocked the whole of Mackroyan," said Noorzia, a resident of the central Kabul suburb.

She said the blast took place at 11:50 am (7:20 GMT).

Other witnesses told AFP that the blast took place on the main road of the district. Police and the interior ministry could not immediately confirm the cause.

Kabul is set to host a major gathering of its international partners -- including about 40 foreign ministers -- on Tuesday, where the government will lay out is plan for the future.

Security forces have thrown a ring of steel around the city to head off any Taliban attacks, with police stationed every few metres along key streets and thousands of extra police officers on duty, authorities said.

Up to 70 international representatives, including US secretary of state Hillary Clinton -- are due to attend the conference, to be co-chaired by President Hamid Karzai and UN secretary-general Ban Ki-moon.

The conference is being billed as a bid by the Afghan government to start a process of transition from dependence on Western backers to running the country alone and responsibly.

Following Taliban attacks on a major domestic conference, or peace jirga, in early June -- which led to the dismissal of the interior minister and the head of the intelligence agency -- authorities said they were taking no chances.

At least two rockets were fired at the jirga as Karzai delivered his opening address. A suicide cell was later cornered and killed by security forces.

"Security is on track," Zemarai Bashary, interior ministry spokesman, said Saturday.

"We're determined to provide good security for the Kabul Conference."

He said "thousands" of police officers, soldiers and intelligence agents had been deployed "in vulnerable areas" from the city centre to remote villages around the capital to thwart any Taliban attack plans.