File photo - A man, exercises on the Long Bien bridge in Hanoi. Long Bien bridge was built in 1903 across the Red River to connect the two parts of Hanoi. Bombed repeatedly during the Vietnam War.

Hanoi - Bombs left over from the Vietnam War have exploded in a central province because of soaring temperatures, authorities said on Wednesday.

The explosion on Monday triggered another two bombs and caused a fire which destroyed five hectares of forest, according to Nguyen Dai Vui, chairman of Phong Dien District in Thua Thien Hue province where the incident occurred.

“Luckily no one was injured,” he said.

Temperatures reached up to 41 degrees Celsius on Monday, the hottest day of the year, according to the National Centre for Hydro-Meteorological Forecasting.

Firefighters did not approach the fire because of the danger of more bombs exploding, Vui said. Instead they isolated the area by clearing trees.

The forest is situated on a former US military base used during the Vietnam War. - Sapa-dpa