Sri Lanka's capital remained jittery Thursday as authorities set off more controlled detonations of suspicious items, soldiers stopped and searched vehicles and some businesses advised staff to stay indoors, four days after suicide bombing attacks killed more than 350 people in and around Colombo.

John Keells Holdings, the parent company of the Cinnamon Grand hotel, one of the sites stricken in the Easter Sunday bombings, told employees at its various hotel properties to stay inside until at least 2:30 p.m. "further to the communications we have received" in an email shared with The Associated Press.

Unusually heavy monsoon rains have flooded Sri Lanka's capital and neighboring districts where mudslides killed at least 13 people, officials said Monday.

The island's western and southern regions experienced heavy rains with more than 100 millimetres (four inches) dumped within about one hour on Sunday, an official at the Disaster Management Centre (DMC) said.

Colombia's leftist FARC rebels declared a unilateral two-month ceasefire Monday as they began talks in Cuba with the Bogota government on ending Latin America's longest-running insurgency.

But the government of President Juan Manuel Santos immediately made clear it would not be bound by the ceasefire and military operations against the FARC would continue.