Authorities in the South American nation of Ecuador have confirmed that an oil spill released about 1,200 barrels into the Pacific, contaminating kilometres of oceanfront.

Rafael Armendariz, transportation manager for the state-owned oil firm Petroecuador, confirmed on Thursday that the incident took place a day earlier when a tank in the marine terminal in the port of Esmeraldas surpassed its capacity.

“It is estimated that around 1,200 barrels were spilled,” Armendariz said at a press conference. “Not all of them fell onto the beach. A part was contained by the pool inside of Petroecuador’s facilities.”

About half of the crude spilled out of Petroecuador’s facilities, spreading across about 4km (2.5 miles) of Las Palmas Beach, a popular destination for recreation and tourists.

An investigation into the cause of the spill is taking place. General Manager Ramon Correa said problems like negligence, mechanical damage or sabotage could not yet be ruled out.

Esmeraldas is about 150km (93 miles) south of Ecuador’s northern border with Colombia. The company says it has controlled 90 percent of the spill’s impact on land and 60 percent at sea through initial cleanup efforts.

Environmental Minister Jose Davalos told the TV station Ecuavisa the spill could affect wildlife such as birds and crustaceans. He expected the cleanup to take about a week.

Davalos noted that he is awaiting an assessment from Petroecuador before deciding on appropriate penalties.