Algeria's government spokesman confirmed some hostages were killed in a continuing military operation at a desert gas plant on Thursday but said troops had been forced to act to free them due to the "diehard" attitude of their captors.

In the first official comments by the government on the day's events, Communication Minister Mohamed Said was quoted as telling state news agency APS that many militants had been killed and that efforts to free foreign hostages were going on.

He acknowledged there had been "several deaths and injuries" among the hostages, but insisted Algeria, which fought a bloody war against Islamists through the 1990s, would not negotiate.