A hotel on Mexico's Caribbean coast where an explosion killed five Canadians and two Mexicans a week ago has been closed to aid the investigation amid suspicions of a possible failure in a gas system, authorities said Saturday.

Officials ordered the 676-room Grand Riviera Princess hotel in Playa del Carmen, south of Cancun, totally shut down for at least a week. An adjoining hotel will also be closed.

"The purpose of the closure is to thoroughly review all the gas hydraulic structures that may have been a cause of the explosion," said Quintana Roo Gov. Felix Gonzalez Canto.

Authorities initially said swamp gases produced by rotting vegetable matter trapped beneath the hotel might have triggered last Sunday's blast, and later suggested an accumulation of sewage gases might have contributed.

Gonzalez Canto said the investigation had produced new evidence of a possible combination of methane and liquefied petroleum gas.

"There is the possibility of both cases being in the area. A [liquefied petroleum gas] line supplies the pool's heating and there is the sewage; the investigation will show which was the cause, if it was one, the other or both," the governor said.

The governor didn't say how many tourists were affected by the closure of the Grand Riviera Princess but local reports said about 450 guests were moved to other hotels on Saturday.

On Tuesday, investigators said they discovered a ruptured sewer line about 10 metres from the area where the blast erupted under the floor of a lounge area. Officials have also noted that the resort was built partly over an area of former mangrove thickets.

Experts say both sewage and rotting sediment from mangroves could produce methane.