A second Dutch flight has arrived in southern Turkey carrying rescue workers and 15 tonnes of equipment to help with the search for survivors following Monday’s devastating earthquakes in Turkey and Syria.

The first Dutch rescue team, with 65 people and eight dogs, arrived in the area on Monday night. ‘As soon as we unleash the dogs they are off, searching for the smell of humans,’ Laura Potma, of the rescue team USAR said.

The death toll in the disaster was put at almost 5,000 on Tuesday morning but experts say the real total will be far higher, with the World Health Organisation suggesting up to 20,000 could have been killed. Six Dutch nationals are missing, the foreign ministry said.

The Dutch Turkish community is also mobilising, collecting clothes, food and mattresses for those who have lost their homes and over €2 million has already been donated to a special Dutch Red Cross bank account to buy supplies.

Ahmed from Drenthe told RTL that his mother and sister were rescued from under four storeys of rubble but that his aunt and her three children are still missing. ‘I have never had such a terrible day,’ said Ahmed, whose interview was interrupted by a phone call with news from the earthquake zone. ‘This is an awful day for all of us.’

The international aid effort is also being stepped up in northern Syria, where the situation is further complicated by the political situation and civil war.

The first quake, measuring 7.8 on the Richter scale, hit in the early hours of Monday while people were asleep. A second 7.5-magnitude tremor then hit at around 13:30 local time.

Turkey’s disaster and emergencies agency AFAD told the BBC 2,660 people from 65 countries have been sent to help in the search and rescue operation.