The death toll from the devastating Iran/Iraq border earthquake was climbing towards 400 by 1615 Tehran time on November 13 as the search for survivors continued amid landslides.

Iranian state news agency Islamic Republic News Agency (IRNA) also quoted an emergency official as saying 6,603 people were injured in Iran alone after the quake—the world's deadliest so far this year and measuring 7.3 on the Richter scale—shook the northern border region from about 21:15 local time on November 12.

Most of those who perished were in Iran's western Kermanshah province, with the Iranian town of Sarpol-e Zahab, about 15km (10 miles) from the Iraqi border, worst hit. The treatment of survivors in the town was hindered by severe damage caused by the quake to its main hospital, Iranian media reported.

The predominantly Kurdish mountainous area typically features homes made of mud bricks, with such dwellings extremely vulnerable to a major earthquake.

Over in Iraq, the worst damage was in the town of Darbandikhan in the Kurdistan Region. "The situation there is very critical," Kurdish Health Minister Rekawt Hama Rasheed told Reuters.

The BBC quoted its correspondent Rami Ruhayem, present in the Kurdistan Region's capital, Irbil, as saying the shaking in the location had lasted for more than a minute. "For a few seconds at first it was barely detectable, I wasn't sure whether it was a minor tremor or just my imagination," he said. "But soon enough it was unmistakable as the building started swaying from side to side."

Tremors from the quake were felt as far away as Tehran, Baghdad, Saudi Arabia, Bahrain, Armenia, Jordan and Kuwait, according to various news agencies.

In 2003, a 6.6-magnitude quake destroyed the historic city of Bam in southeastern Iran, with the loss of 26,000 lives and the displacing of 76,000.

Geologists say northwestern Iran suffers quakes because the Arabia tectonic plate is pushing the Eurasia tectonic plate north by a couple of centimetres a year.

Tehran with an estimated 12mn inhabitants is the most secure Iranian city in terms of earthquake building resistance. All new buildings put up in the capital must meet modern regulations to protect residents and workers from substantial earthquakes.