Maduro shut the border on security grounds. Many Colombians were expelled, and bilateral trade has since fallen.

The UN special envoy for Syria said a chlorine attack, if confirmed, would amount to a "war crime".

The capture of Sirte would be a major setback for Islamic State, ousting the jihadist group from the only city in Libya where it established total control.

Police believe the series of blasts were acts of local sabotage and not linked to any international militant group.