Iran has called for Pakistan to crack down on a Sunni Muslim group behind a suicide attack in Iran's Sistan-Baluchestan region.
Mostafa Mohammad Najjar, Iran's interior minister, arrived
in neighbouring Pakistan on Friday to meet Rehman Malik, his Pakistani counterpart, as he called for the leader of the Sunni Muslim Jundollah group to be handed over.
Jundollah, or the "Soldiers of God", has reportedly claimed it carried out a bombing that killed 42 people in the city of Pisheen this week,
Iran says the group which is led by Abd ul-Malik Rigi, has bases in Pakistan.
"We have documents that show Rigi travels readily to Pakistan ... we are here to ask Pakistan to hand over Rigi to Iran," Najjar told state television in Pakistan.
"It [sheltering Rigi] is not in the interest of the two countries' good neighbourly relations."
A statement from the Pakistani interior ministry following the talks made no reference to the request for Islamabad to hand over Rigi, but instead denied any Pakistani backing for Jundollah.
"Pakistan would never allow its territory for any terrorist activity against Iran or any other country," an interior ministry statement quoted Malik as telling Najjar.
In the past, Islamabad has denied that Rigi is in Pakistan and has accused the Jundollah of trying to undermine its close ties with Tehran.
Iran has previously suggested that the fighters have links with Pakistani intelligence, and also accuses the United States and Britain of backing Jundollah.
Washington, London and Islamabad have all denied involvement.
Iran's remote Sistan-Baluchestan province has seen an increase in bombings and clashes between security forces, ethnic Baluch Sunni fighters and drug traffickers.
Many Baluchs in the Iranian province feel more closely aligned with Baluchs in Pakistan's neighbouring Balochistan than with Iran's majority, mainly Shia, Persian population.
Iranian state television said on Tuesday that three people had been detained in connection with the Pisheen bombing, but gave no details.
At least 15 Revolutionary Guards, including six senior commanders, and 27 other people were killed in the blast.