A Pakistani cleric holed up in an Islamabad mosque said on Thursday he and his student followers were willing to surrender, after three days of violence in which 19 people have died.
But authorities rejected his offer, saying his attempt to attach conditions was unacceptable and insisting he release women and children human shields.
Violence erupted outside the Red Mosque, or Lal Masjid, in the capital on Tuesday after a months-long stand-off between the authorities and the Taliban-supporting clerics and their thousands of followers, some of them armed.
There were intermittent clashes and several loud explosions through the day on Thursday. Interior Ministry spokesman Javed Iqbal Cheema said some holes had been blasted in the compound walls.
Hundreds of troops and police are surrounding the students in their fortified mosque in a leafy neighborhood in the centre of Islamabad.
Cleric Abdul Rashid Ghazi, speaking in a telephone interview from the mosque, said he and his followers would surrender if those who were not members of banned terrorist groups could go free, and if he could remain in the mosque with his sick mother.
"If they are linked to any banned organization, it can be verified ... those who are not should be let go," he told Geo Television.
Suggestions members of militant groups were among his students were propaganda, he said, adding: "I and my mother should be allowed to live in the mosque until I make some alternative arrangements."
But the government ruled out any conditions.