The chief of Algeria's national police was shot dead on Thursday at his headquarters by another police official who was acting in a moment of insanity, the Interior Ministry said.

'The death of Ali Tounsi ... took place during a working session, in the course of which a police official, apparently gripped by an attack of madness, used his weapon and fatally wounded Colonel Tounsi,' Algeria's official APS news agency quoted a ministry statement as saying.

Earlier, a security source told Reuters that Tounsi, who had been national police chief for more than a decade, was shot inside his office by a senior police official with whom he was having an argument.

'This guy was unhappy, he took out his pistol and he fired it,' the source said. 'Police officers nearby fired back.'

The Interior Ministry statement said that after shooting the police chief, the attacker shot himself and was now in serious condition in hospital. It made no mention of police firing back.

A Reuters photographer outside national police headquarters, in the center of the capital, said an unusually large number of police were there, including elite armed-response officers.-Reuters