UN chief Ban Ki-moon has said he will launch "very shortly" an independent inquiry into the killing of Pakistani ex-Prime Minister Benazir Bhutto, BBC reported.
Mr Ban made the comments came after talks with senior Pakistani officials.
Ms Bhutto was killed in a suicide attack on a rally in 2007. Her death triggered riots across the country.
Islamabad's current government has rejected official Pakistani reports on the killing, and called for a wider inquiry by the UN.
Five people have been arrested in connection with the killing, but no-one has been convicted.
After talks in Islamabad, Mr Ban said: "I intend to establish very shortly an independent commission of inquiry headed by a very distinguished person, whom I'm going to nominate in a very short period of time."
"I have been in consultation with the government of Pakistan on its request for the establishment of a commission of inquiry on the assassination of former Prime Minister Benazir Bhutto.
"This is a crime that shocked and offended the world, and I know this is a matter of great importance to the government and people of Pakistan," Mr Ban said.
The Pakistani government - dominated by Ms Bhutto's PPP party - and US officials have accused tribal warlord Baitullah Mehsud of plotting the attack on Ms Bhutto, although he denies the allegation.
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".
Mr Ban's visit to Pakistan is his first since taking office in 2007.
His trip 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 earlier said that in Pakistan Mr Ban was also expected to discuss last year's attacks on the Indian city of Mumbai (Bombay) which left more than 170 people dead.
Also on the agenda was 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 began his regional visit earlier in the day in Afghanistan, where he said the country would be a priority for the UN in 2009.
After Pakistan, he will visit India.