US envoy Richard Holbrooke was set to hold key talks in Afghanistan on Saturday aimed at stepping up the fight against the escalating Taliban-led insurgency.
President Barack Obama's regional troubleshooter is making his first on-the-job visit to the country in the wake of coordinated Taliban attacks on government offices in Kabul that killed 26 people and left eight attackers dead.
Some analysts suggest the triple attacks may have been an attempt by the Taliban to overshadow Holbrooke's trip and underline their strength despite the efforts of around 70,000 international troops based in Afghanistan.
Holbrooke, who arrived on Friday, was expected to have discussions with a range of international and Afghan authorities including President Hamid Karzai, whose relations with Washington have been strained.
Britain's new special representative to Afghanistan and Pakistan, current ambassador to Afghanistan Sherard Cowper-Coles, is also in Kabul.
As Holbrooke held talks on Friday, authorities said five Afghan civilians were killed in a battle with insurgents in the southern province of Uruzgan where a US-led coalition soldier died in a separate incident.
Australian troops based in Uruzgan said the five were children but Afghan police said two were adults and that all came from the same family.
The incident underscores the complexity of the challenge in Afghanistan where mounting civilian casualties in operations against insurgents, who live among ordinary people, risk public support for the government and its allies.
Holbrooke's regional tour -- he flew in from Pakistan and will travel on to India -- is part of a major focus on South Asia from the Obama administration to address the spiralling violence.
The magnitude of the problem -- which Holbrooke has warned could prove tougher than Iraq -- was highlighted by Dennis Blair, the new US director of national intelligence.
Delivering an annual threat assessment to Congress, he said the Taliban-dominated insurgency had expanded in scope over the past year -- moving into previously peaceful areas around Kabul and elsewhere.
His report said the security situation had worsened in many eastern areas, as well as the south and northwest, and predicted insurgents would likely make a concerted effort to disrupt presidential elections due on August 20.
The Kabul government's inability to develop honest, effective and loyal institutions at local and district level "erodes its popular legitimacy and increases the influence of local warlords and the Taliban," it said.
Blair's report noted similar problems in neighbouring Pakistan, mainly in the restive tribal border areas, which US and Afghan officials regard as safe havens for Al-Qaeda and Taliban militants.
Pakistani President Asif Ali Zardari warned overnight that Taliban militants were present in "huge amounts" of the country and the military was "fighting for the survival of Pakistan."
A US-led coalition ousted the Taliban from power in Kabul in late 2001, but rampant unrest and the fragility of the Kabul government continue to lock down tens of thousands of international troops in Afghanistan.
Obama is expected to decide soon on deploying extra troops.
Military officials suggest 15-30,000 more US soldiers may head to southern Afghanistan, where Taliban violence is worst and a number of districts have fallen from government control.
Holbrooke has said he will use his tour to listen and learn before reporting back to Obama and US Secretary of State Hillary Clinton.