37 foreigners die at Algeria gas plant, seven missing - PM
Sellal also told a news conference that a Canadian had coordinated the attack by Islamists on the site near the Libyan border.
"A Canadian was among the militants. He was coordinating the attack," Sellal said, adding that the raiders had threatened to blow up the gas installation.
Earlier an Algerian security source told Reuters that documents found on the bodies of two militants had identified them as Canadians, as special forces scoured the plant following Saturday's bloody end to the crisis.
Canada's foreign affairs department said it was seeking information, but referred to the possible involvement of only one Canadian.
Sellal said 29 Islamists had been killed in the siege, which Algerian forces ended on Saturday by storming the plant, and three had been captured alive.
American, British, French, Japanese, Norwegian, Filipino and Romanian workers are dead or missing after the attack, for which veteran Islamist fighter Mokhtar Belmokhtar has claimed responsibility on behalf of al Qaeda.
A Japanese government source said earlier that the Algerian government had told Tokyo nine Japanese had been killed, the biggest toll so far among foreigners at the plant. Six Filipinos died and four were wounded, a government spokesman in Manila said.
Norwegian International Development Minister Heikki Holmaas also said his stepfather, Tore Bech, was among the missing and presumed dead. Bech was a manager at the site for the Norwegian energy company Statoil.
Sellal said the jihadists had planned the attack two months ago in neighbouring Mali, where French forces began fighting Islamists this month.
Initially the raiders in Algeria had tried to hijack a bus carrying foreign workers to a nearby airport and take them hostage. "They started firing at the bus and received a severe response from the soldiers guarding the bus," Sellal said. "They failed to achieve their objective, which was to kidnap foreign workers from the bus."
(Reporting by Lamine Chikhi; additional reporting by David Ljunggren in Ottawa; editing by David Stamp)