Bolivia's president said Saturday he would file a suit against Chile at the International Court of Justice "in the coming days" in a bid to reclaim access to the sea lost in a 19th century war.
During an event in honor of the "Day of the Sea" -- commemorating the war that left impoverished Bolivia landlocked -- President Evo Morales said he hoped to resolve the dispute through "peaceful settlement mechanisms."
Morales vowed similar action on the occasion two years ago.
"I have decided that in the coming days, a commission will travel to The Hague to file a suit to regain sovereignty over access to the sea," he said during a speech at the start of celebrations marked by civilian, military and police parades.
"This maritime claim is the inalienable and indefensible right of the Bolivia people."
Shortly after the announcement, Chilean President Sebastian Pinera vowed to stand firm.
"Faced with any claims that Bolivia may bring before international tribunals, Chile and its people will defend with the full strength of national unity, history and truth its territory, its sea, its skies and its sovereignty," Pinera said.
Bolivia, the poorest country in South America today, is hoping to recover about 400 kilometers (250 miles) of coastline lost in the 1879-1884 War of the Pacific.
Chile rejects the claims, saying that the two countries signed a peace and friendship treaty in 1904 that set bilateral border limits.
Previous attempts to negotiate the redrawing of the border have failed.
The two countries have had limited diplomatic relations since 1978, and tensions rose earlier this year after Chile arrested three Bolivian soldiers just inside its border.
The soldiers, who claimed they were pursuing smugglers, were later released.
Morales said earlier this month that bilateral negotiations with Chile over the border dispute would be a "waste of time."