Three children were killed in a mine explosion in Yemen's oil-rich northern province of Marib, a local government official said Wednesday.

The official, who spoke on condition of anonymity, said the tragedy occurred on Tuesday when the children from the same family were playing in an area near the As-Suwayda camp for displaced people and accidentally triggered a landmine.

The As-Suwayda camp is one of the largest displacement camps in Marib, providing shelter for around 2,000 displaced families.

The mine explosion is a reminder of the dangers faced by civilians, especially children, in Yemen's long-running civil war, which left the country littered with landmines, making it one of the most heavily mined countries in the world.

In April, the Yemeni government made an urgent appeal for international assistance to clear landmines and other explosive remnants of war.

Yemeni demining experts said more than 1 million landmines have been laid since the outbreak of the civil war in late 2014 when the Houthi militia took control of several northern provinces and forced the Yemeni government out of the capital Sanaa.