Terrorists fired grenades at troops that have cordoned off a school in southern Russia where hundreds of hostages, including women and children, were holed up without food for the third day on Friday, even as authorities ruled out the use of force to end the standoff.

Contacts with the militants broke off overnight but the officials said they hoped the talks would resume on Friday.

"We are hoping for further intensification of the process," Lez Dzugayev of the North Ossetian presidential office was quoted as saying by Itar-Tass.

The ultras, who are holding over 300 people hostage in the Beslan school since Wednesday, fired several shots with their grenade launchers and injured one police personnel.

"The terrorists said they suspected some movement in the area. We calmed them down and promised that it is not so," Dzugayev said while ruling out any use of force.

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"As long as there is chance to negotiate, any use of force is ruled out," he said adding, "It is an extreme measure and it is not being considered."

Dzugayev said the terrorists in the Beslan attack might be from Chechnya or Ingushetia.

He said the hostage-takers had released 26 women and children on Thursday. However, they continue to refuse food for those still inside the building.

"Fresh food is kept near the school building in case there is a chance to hand it over to the children," Dzugayev said.

Russian President Vladimir Putin has said he would try to end the standoff, which has claimed 12 lives so far, through peaceful means and ensure the safety of hostages.

Anxious family members of the hostages spent the night at the House of Culture, waiting for some news.

Meanwhile, security has been tightened at schools across Russia in the wake of the crises, the education ministry said on Friday. Also, in the wake of the hostage crises, authorities have decided to cancel all mass festivities, Itar Tass said quoting an official statement in Moscow.

The International Committee of the Red Cross (ICRC) has called for the release of the hostages. It has offered to provide relief to the victims but is yet to hear from the Russian government or the hostage-takers to act as 'humanitarian intermediary'.

UN Representative for Children and Armed Conflict Olara A Otunnu said, "It is unacceptable that children anywhere should be subjected to these practices of brutalisation."

UN Secretary-General Kofi Annan had on Thursday called the hostage-taking a 'criminal and heinous' act.

The US has strongly condemned the 'act of terror' and asserted there was 'no excuse and no justification' for the hostage taking.

Russia has been reeling from a wave of terrorist attacks since August 25 that have killed over 100 people.