More than one million refugees and migrants have reached Europe by sea since the start of 2015, according to the United Nations refugee agency (UNHCR).

More than 80% of the 1,000,573 people arrived in Greece, with the majority landing on Lesbos island.

Around 844,000 travelled to Greece from Turkey. Most of the others, around 150,000, crossed the Mediterranean from Libya to Italy.

The migrant crisis is Europe's worst since World War Two.

The UNHCR says the number of sea arrivals has increased greatly since 2014. During that year around 216,000 made the crossing.

"Increasing numbers of refugees and migrants take their chances aboard unseaworthy boats and dinghies in a desperate bid to reach Europe," the UNHCR said on its website.

"The vast majority of those attempting this dangerous crossing are in need of international protection, fleeing war, violence and persecution in their country of origin."

The UN agency says almost half of migrants crossing the Med came from Syria. Another 21% came from Afghanistan.

The number of those dead or missing at sea is now at 3,735.

A report published by the UNHCR and the International Organisation for Migration last week said an estimated 34,000 migrants crossed from Turkey into Bulgaria and Greece by land since the start of the year.