More than 21,000 people are now known to have died in Monday's earthquakes in Turkey and Syria

More than 21,000 people are now known to have died in Monday's earthquakes in Turkey and Syria, which Turkey's president has called "the disaster of the century".

A massive international relief effort is gathering steam.

The World Bank pledged $1.78 billion (£1.38 billion) in aid to Turkey on Thursday, including immediate funding for rebuilding basic infrastructure and assisting those affected by the earthquakes.

Meanwhile, the efforts of 100,000 or more rescue workers on the ground are hampered by logistical challenges such as vehicle shortages and damaged roads.