Pakistan has denied Iranian claims that the government is aware of the fact that Abdolmalek Rigi -- the alleged mastermind of the terror attack in Pishin on Sunday --- is hiding in Balochistan. Rigi is the chief of the underground Sunni outfit group Jundallah which claimed responsibility for the attack in Iran's Sunni-majority Sistan-Baluchistan province.
At least 42 people were killed in the attack, including seven members of Iran's elite Revolutionary Guards.
Iranian President Mahmoud Ahmadinejad too accused Pakistan of having links to the bombers who carried out the attack.
"We have heard that certain officials in Pakistan cooperate with the main agents of these terrorist attacks in eastern parts of the country. It is our right to ask (for the extradition) of criminals," Ahmadinejad was quoted by Iran's Press TV as saying.
Earlier, Iran's Ambassador to Pakistan Mashallah Shakeri told reporters that Jundallah chief Abdolmalek Rigi was present in Pakistan.
The Daily Times quoted Pakistan's foreign ministry spokesman Abdul Basit as saying that the Iranian ambassador's claim, that the Jundullah chief is hiding in Pakistan, could harm relations between both countries.
Pakistan and Iran were cooperating in the war on terror, and both countries enjoyed 'friendly relations', he said.
Basit said that the war on terror in South Waziristan reflected Pakistan's commitment not to allow its territory to be used for activities against any other country.
"Pakistan is not involved in terrorist activities ... we are striving hard to eradicate the menace," he said.
Iran's Interior Minister Mustafa Muhammed Najjar too took up the matter with his Pakistani counterpart Rehman Malik during a phone conversation.
Najjad called Malik and sought Pakistan's assistance in arresting Rigi. Malik assured the Iranian government of Pakistan's full cooperation in investigating the suicide bombing but asserted that Rigi was not in the country.
He said every effort would be made to capture those behind Sunday's attack.
Iranian officials have complained on several occasions that Jundallah operatives are active in Pakistan's southwestern Balochistan, which borders Sistan-Baluchistan.
President Asif Ali Zardari and Prime Minister Yousuf Raza Gilani too stepped in to defuse tensions. Both condemned the suicide attack in Iran and Gilani expressed solidarity with the government and people of the neighbouring country.
A suicide bomber blew himself up during a conference between Sunni and Shia tribal leaders in Pishin city in Sistan-Baluchistan on Sunday.