Fifteen Colombian soldiers have been killed in an ambush by leftist FARC rebels, the country's president said Sunday, raising concerns about peace talks launched last year.

"Our hearts are with the families of the fifteen heroes who sacrificed their lives in Arauca for the tranquility and security of their fellow citizens," President Juan Manuel Santos said.

The International Committee of the Red Cross said Saturday it has made contact in Colombia with leftist guerrillas who said they wanted to release a captured U.S. ex-soldier.

The Revolutionary Armed Forces of Colombia (FARC) said Friday it has been holding Kevin Scott Sutay since June 20 in the southern department of Guaviare.

Colombian FARC guerrillas said Friday they captured a U.S. soldier last month and are offering his release as a "gesture" toward peace with Bogota.

In a statement on their website, the leftist rebels identified their captive as Kevin Scott Sutay, and said they captured him on June 20 in the municipality of Retorno, in the southern department of Guaviare.

Spanish police said Thursday they had smashed an international cocaine ring in a two-year operation with other forces that led to the arrests of 74 people in Spain, Brazil and Colombia.

Police seized 575 kilograms (1,270 pounds) of the drug and closed five secret laboratories in a global swoop together with U.S., Brazilian and French police.

Colombia said it was concerned about reports it was the target of U.S. electronic surveillance and will seek an explanation from its close ally.

The foreign ministry, in a statement late Tuesday, said Colombia rejected "acts of espionage that violate people's right to privacy and international conventions on telecommunications."

U.S. electronic espionage operations have targeted a variety of Latin American countries besides regional heavyweight Brazil, including key Washington ally Colombia and its nemesis Venezuela, a Brazilian newspaper reported Tuesday.

The report in O Globo was the latest in a series on U.S. electronic surveillance operations based on documents leaked by fugitive former NSA contractor Edward Snowden.

A drug trafficker believed by Italian investigators to be the biggest cocaine smuggler in the world was deported back to Italy from Colombia on Saturday after being arrested in a Bogota shopping mall with fake Venezuelan papers.

Media reports said Roberto Pannunzi, who fled from an Italian prison in 2010, smiled as he arrived at Rome's Fiumicino airport on a scheduled Alitalia flight escorted by Italian and Colombian police and dressed in a white polo shirt with dark trousers.

A DEA agent has died in an apparent robbery attempt in Colombia, U.S. Ambassador Michael McKinley said Friday. Colombian authorities said the American agent was stabbed four times.

McKinley told local Radio Caracol that the robbery attempt occurred after the anti-drug agent left a meeting with friends at a Bogota restaurant and got into a taxi.

Palestinian leader Mahmoud Abbas met Colombian President Juan Manuel Santos in the occupied West Bank on Tuesday, a day after Israel's closest South American ally signed a free trade deal with the Jewish state.

Colombia was one of a minority of states to abstain in a vote on upgrading the Palestinians' status at the United Nations in November which passed with overwhelming international support.

Colombia's chief negotiator in peace talks with the country's largest leftist rebel group on Friday praised Venezuela's role in the process after Caracas threatened to pull out over a diplomatic spat.

"The role of Venezuela has been very important in the dialogue and we do not want this to be interrupted," Humberto de la Calle told Radio Caracol.