BERLIN (Reuters) - Germany’s arch conservative Christian Social Union (CSU) party, a junior partner in Chancellor Angela Merkel’s coalition, wants to close off the Mediterranean Sea route for migrants by sending them back to Africa rather than allowing them to stay in Europe.

A christmas tree lays on the street beside the empty Christmas market in Berlin, Germany, December 21, 2016, after a truck ploughed through a crowd at the Christmas market on Monday night. REUTERS/Hannibal Hanschke

As a reaction to the Dec. 19 truck attack in Berlin, the Bavarian sister party to Merkel’s Christian Democrats (CDU) has drafted a paper calling for a change in policies that allow refugees rescued from endangered vessels to remain in Europe.

The CSU has long bristled at Merkel’s open-door policies that allowed into Germany about 1.1 million refugees from Syria, Iraq, Afghanistan and elsewhere since mid-2015. Ignoring her objections, it insist on a limit of 200,000 refugees per year.

The attack last week in Berlin in which an asylum-seeker from Tunisia killed 12 people has heightened fears in Germany that there could be more security threats among the refugees.

With a election due in September, the CSU is worried about losing votes to the fast-growing far-right Alternative for Germany (AfD) party that takes a hard line against refugees and has directly blamed Merkel’s refugee policies for the attack.

“The automatism that all refugees are taken to Europe needs to be stopped,” reads the internal paper by the CSU deputies in parliament, as quoted in the Rheinische Post daily. “That’s the only way going to stop organized crime on the Mediterranean.”

The CSU proposal is not new. Interior Thomas de Maiziere, a leader in Merkel’s CDU, in October proposed returning migrants to Africa where their claims for asylum in the EU can be studied as an antidote to the profitable smuggling trade.

De Maiziere’s ministry said there were no concrete plans or discussions at the EU-level about the proposal.

At a meeting in Brussels on Dec. 15, the EU said it was seeking money-for-migration deals to curtail migration from Africa through the Mediterranean. The bloc has also strengthened control of its external borders and is trying to deport more people who make it to Europe but have no case for asylum.

But they remained divided over how to share the burden of caring for those who are already in the EU.

A record 5,000 migrants are believed to have drowned in the Mediterranean Sea this year, the International Organization for Migration (IOM) and the U.N. refugee agency UNHCR said last week. Just under 3,800 migrants perished at sea during all of 2015, according to IOM figures.

IOM figures show 358,403 migrants and refugees had entered Europe by sea in 2016 up to and including Dec. 21, arriving mostly in Greece and Italy.