Three unexploded bombs discovered in Bangkok and surrounding suburbs have been defused by police.

One of them was found in front of a school and another in a shopping centre.

The discoveries follow a series of grenade blasts in recent weeks across the Thai capital.

A bomb hoax on a Thai Airways flight from Bangkok to Los Angeles was not related to incidents in the city, according to Suthep Thaugsuban, deputy prime minister in charge of national security.

Bangkok remains under emergency rule following street clashes in April and May during anti-government protests.

Thailand put more than 460 locations across the city on high alert last Friday, sending police, soldiers and city officials onto the streets in a bid to increase the security presence.

Royal palaces, government buildings, power plants and public transport are receiving protection from the Centre for Resolution of Emergency Situation (CRES), the body set up to monitor security in response to the unrest.

Bangkok is one of seven areas under emergency rule introduced on April 7 as a response to the “Red Shirt” rallies that later left 91 people dead and about 1,900 injured in clashes between protesters and the army.

Five bombings in recent weeks, leaving one dead and 13 injured, have raised doubts over when the emergency rule can be lifted in the capital.