Russian President Vladimir Putin on Saturday called on Europe to contribute financially to the reconstruction of Syria to allow millions of refugees to return home.

"We need to strengthen the humanitarian effort in the Syrian conflict," he said ahead of a meeting with his German counterpart Angela Merkel at the government retreat of Meseberg castle 70km north of Berlin.

"By that, I mean above all humanitarian aid to the Syrian people, and help the regions where refugees living abroad can return to."

Rebuilding Syria will cost at least $250bn, according to a UN estimate. Earlier this month, a Russian suggestion that the United States and Russia form a joint group to finance infrastructure renovation in Syria was met with an icy reception, according to a US memo seen by Reuters.

Syria's civil war has left much of the country in ruins (AFP/file photo)

There are currently one million refugees in Jordan, the same number in Lebanon, and three million in Turkey, Putin said.

Merkel said the priority in Syria was "to avoid a humanitarian catastrophe," particularly in the Idlib region, which is held by rebel groups and militants.

Germany has accepted hundreds of thousands of migrants since 2015, the height of the migration crisis that has weakened Angela Merkel politically and split the European Union.

"This is potentially a huge burden for Europe," Putin said.

"That's why we have to do everything to get these people back home," he added, emphasising the need to properly restore basic services such as water supplies and health care.

The Syria conflict has killed about half a million people, driven about 5.6 million people out of the country and displaced 6.6 million within it.

The talks, whose topics included Syria, the Ukraine and a Russian gas pipeline, ended later in the day with no clear-cut progress. Kremlin spokesman Dmitry Peskov told reporters no agreements were reached, but the meeting had been intended to simply "check the watches" after Merkel's meeting with Putin in the Black Sea resort of Sochi in May.