US hails Greek economic efforts: Kerry

US Secretary of State John Kerry on Friday hailed troubled Greece's economic recovery efforts in the midst of a huge migration challenge as he arrived in Athens for a brief visit.

"I appreciate the way you are approaching economic reforms efforts (...) it is not easy," Kerry told Greek Prime Minister Alexis Tsipras.

"I am very happy to be here and I thank you first of all for the great partnership on a number of security issues we are working closely together and I know you are dealing with (...) challenge of migration," he said.

Kerry is spending a few hours in Athens on the closing leg of a regional tour that also saw stops in Cyprus, Serbia and Kosovo.

The leftist government of Alexis Tsipras is trying to apply an unpopular third EU economic bailout enacted in July in return for safeguarding the country's place in the eurozone.

At the same time, Greece has found itself on the front lines of the greatest migration influx facing Europe since the Second World War, a challenge compounded by security fears that jihadists are entering the continent posing as refugees from war-torn Syria.