Several funerals of Saturday's victims have been held

Officers recovered over 30 kilogrammes (66lb) of explosives, Interior Minister Boris Gryzlov said, adding that this was enough to equip 30 suicide bombers.

The two - who were arrested 150 kilometres (90 miles) north-west of Moscow - may have had accomplices, Mr Gryzlov said.

The interior minister also said that the authorities had evidence pointing them to the person who ordered Saturday's attack, in which two female suicide bombers killed 14 people.

Efforts to find the organisers of the attack are continuing, with mobile phone operators in Moscow saying they have been ordered to stop encoding their signals to allow eavesdropping by security personnel on all calls in the city and its environs for a 24-hour period.

Screen changes

Mobile phone users in Moscow complained overnight about poor signals on all networks.

Experts believe this was caused by operators switching their services from a secure to non-secure mode.

They advised customers to check the screens of their phones which are supposed to alert them about such changes with special symbols.

Investigators searching for clues in the suicide bombing case are pinning their hopes on a SIM card from a destroyed mobile phone found on the scene of the Saturday blast.

It is thought to have belonged to one of the suicide bombers.

Police are trying to trace all calls made from that phone.

They believe the explosive devices carried by the two female suicide bombers could have been set off remotely as they tried to enter the festival grounds.

Funerals

Russian legislation allows for temporary eavesdropping on mobile phones as part of anti-terrorist measures.

Signal-encoding of mobile phone calls was previously switched off during the hostage siege in a Moscow theatre last October, and during the St Petersburg summit last May.

Moscow held a day of mourning for the victims of the bombing on Tuesday, and some funerals have already been held.

Dozens of people are still being treated in hospital for their injuries. One woman died in hospital, raising the number of dead to 14.

Moscow officials have blamed the attacks - the first suicide bombings in the Russian capital - on Chechen rebels.

President Vladimir Putin has vowed to root out Chechen militants and show them no mercy.

But critics point out that he has said that before, with no sign so far that his tactics have borne much fruit.

The BBC's Sarah Rainsford in Moscow says Saturday's suicide attacks suggest a growing determination among rebel groups to carry their fight to the heart of Russia.