The death rate for migrants attempting to reach Europe has risen even though the numbers trying to make the crossing has fallen, the UN Refugee Agency has warned.

More than 1,600 people have died or gone missing this year, the UNHCR said in a new report, with the rate of fatalities rising sharply, particularly in the Mediterranean Sea.

For every 18 people crossing to Europe over the central Mediterranean between January and July 2018, one person died. Over the same period in 2017, there was one death for each 42 refugees and migrants attempting the crossing.

The UN report blamed the increase in the death rate on fewer NGO boats being active on the Libyan coast. In 2017, there were eight but now there are just two. The Libyan Coast Guard, which has two patrol boats, is now the main organisation intervening off the Libyan coast.

In practice this has meant migrants travelling in unsafe vessels for longer and further with less likelihood of being detected and with fewer boats able to help, the UNHCR said.