The UN's secretary-general has begun a key regional visit in Kabul, with a pledge that Afghanistan will be a priority this year.
Ban Ki-moon's visit to Kabul was unannounced. He said the UN was strongly committed to delivering peace in Afghanistan, reported BBC.
He is later due in Pakistan where he may announce a probe into the murder of former Pakistani PM Benazir Bhutto.
Her supporters have consistently called for a UN probe into her death in 2007.
In Kabul, Mr Ban pledged Afghanistan the UN's full backing ahead of elections due in August this year.
"For the United Nations, Afghanistan will be a priority in 2009," Mr Ban said at a joint news conference with President Hamid Karzai.
"I am here to demonstrate and to convey my strong commitment and support for peace and stability for... Afghanistan's people," he said.
He said there had to be improved co-ordination among Afghanistan's many international donors to maintain progress and make "tangible changes" to people's lives.
Increasing violence in the country has become a major concern for the UN and Western powers.
Mr Ban will also meet Nato commanders and international officials to discuss improving security.
The new US administration of President Barack Obama is trying to persuade allies to send more troops for the Nato-led operation there.
Mr Ban's visit to Pakistan will be the first since he took office in 2007.
A foreign ministry spokesman told the BBC Urdu service that Mr Ban may announce the formation of a three-member commission to investigate Ms Bhutto's killing in December 2007.
Ms Bhutto was killed shortly after addressing an election rally
She was the victim of a gun and bomb attack as she was leaving a rally of her Pakistan People's Party (PPP) in the garrison town of Rawalpindi.
The Pakistani government and US officials have accused tribal warlord Baitullah Mehsud of plotting the attack on Ms Bhutto, although he denies the charge.
In December, a spokesman for Mr Ban said that the UN leader was optimistic that a commission into her killing could be established, but more consultations with Pakistan were needed to examine its "scope and mandate".
However the BBC's M Ilyas Khan in Islamabad says that the announcement is by no means a certainty because Mr Ban only has a short time in the country to address several pressing problems, including the kidnapping of a UN official in the province of Balochistan on Monday.
Mr Ban has called for the "immediate and safe release" of John Solecki, the head of the UN refugee agency (UNHCR) in the city of Quetta who was snatched at gunpoint after his driver was killed.
Mr Ban will meet Prime Minister Yousuf Raza Gilani and President Asif Ali Zardari before leaving for India.
His visit comes amid growing unrest in Pakistan's border areas, with Taleban rebels attacking Nato supply routes into Afghanistan while government forces engage the Taleban in the Swat valley of North West Frontier Province.
Officials say that Mr Ban is also expected to discuss last year's attacks on the Indian city of Mumbai (Bombay) which left more than 170 people dead.