Kabul  - US Defence Secretary Robert Gates arrived in Kabul on a surprise visit Tuesday for talks with coalition commanders and Afghan leader Hamid Karzai amid growing concerns that the resurgent Taliban are gaining strength.

Afghan and international military sources revealed that Gates was expected to hold talks with US-led coalition commanders on the ground to get first hand information on fight against the resurgent Taliban.

The top US army chief was also scheduled to meet President Karzai on Wednesday to discuss the rising civilian casualties caused mostly in US aerial bombing, Afghan officials said.

Relations between the US and Afghan government were strained after the US military had denied the killing of a large number of Afghan civilians in an air raid in western Afghanistan late last month.

The Afghan government said that more than 90 civilians mostly children were killed in the airstrike. The UN investigative team also backed the Afghan government's findings.

The US military later announced that it would send a US general to Afghanistan to re-investigate after videos wmerged showing the bodies of the civilians including at least ten children. Initially the military said that up to seven civilians and 30-35 militants were killed in the attack.

Civilian casualties during the international military operation against Taliban have become a matter of great concerns for Karzai, who believes the mounting civilian deaths will erode public support for his government.

UN High Commissioner for Human Rights Navi Pillay said in a statement on Tuesday that 1,445 civilians were killed in the first eight months of this year, showing an increase of 39 percent compared to the same period in 2007.

Pillay said that 330 civilians were killed in only in the month of August, making it the deadliest period for civilians since the ouster of Taliban regime in late 2001.

Around 800 deaths - or 55 per cent of the total number of civilian killings in the first eight months of this year - were attributed to the Taliban insurgents, which is nearly double the 462 deaths for which the militants were held responsible in the same period last year. (dpa)