Firefighters have contained a massive refinery fire on Nicaragua's Pacific coast, officials said Sunday.

The blaze at the Puma Energy facility ignited Wednesday when one of four huge fuel tanks exploded at the site in the port of Puerto Sandino, some 70 kilometers (40 miles) northwest of the capital Managua. A second tank ignited on Thursday.

"For all practical purposes, we have extinguished the fire," said Salvador Gallo, deputy director of the national firefighter department, who said however that there have been some "small, residual" flareups. 

Puma Energy expects that any remaining waste oil in the tanks would finish burning Sunday, a source from the company's Managua office told AFP.

Each of the damaged fuel tanks is capable of holding some 144,000 barrels, although the company ruled out a fuel shortage following the fire.

The disaster did not cause any deaths or injuries, but government medical brigades have been dispatched to the area to assess the impact of smoke exposure on the health of nearby residents.

Oil from the spill could be seen on the coast and in surrounding vegetation, according to environmentalists, who said the damage to sensitive habitat could take years to reverse. 

Surrounding beaches are home to important nesting grounds for several turtle species, while the Puerto Sandino coast and nearby Miramar beach produce 12 percent of Nicaragua's salt.

Puma Energy, a majority Dutch and Angolan-owned company with headquarters in Switzerland, bought the refinery in 2011. It had previously been run by the US group Exxon.