German Chancellor Angela Merkel said on Monday that Berlin wanted to support Italy in its efforts to reduce the number of migrants arriving on its shores by possibly handling asylum requests for Europe in non-European countries such as Libya.

"Italy is one of the countries that is receiving a lot of refugees as a first arrival country," Merkel told reporters ahead of talks with Italian Prime Minister Giuseppe Conte in Berlin.

"Especially the question how we can achieve a stable government in Libya... and how we can, if necessary, carry out asylum-related proceedings already there. These are all questions that we will discuss in the coming months and where we want to work very closely together."

Earlier on Monday, Merkel's conservative Bavarian allies agreed to give her a two-week breathing space to find a European solution to a row over immigration that threatens to scupper her three-month-old coalition government.

Bavaria's Christian Social Union (CSU), anxious about losing votes to a new right-wing party in an October regional election, wants a ban on admitting migrants into Germany who have already registered in another EU country. Merkel opposes such a ban.

US President Donald Trump, defending his own tough anti-immigrant polices, waded into Germany's debate on Monday with a series of tweets criticising Merkel's open-border policy as a "big mistake" that had fuelled crime in Europe.

The CSU leadership agreed at a meeting in Munich to delay introducing their entry ban until after a June 28-29 European Union summit, allowing Merkel time to seek an EU-wide solution.

Merkel opposes any unilateral move by German Interior Minister Horst Seehofer, who is also CSU chairman, that would reverse her 2015 open-door policy on migrants and undermine her authority. Monday's compromise means he can introduce immediate expulsion for one subset of migrants.

"We wish the chancellor much luck," Seehofer told a news conference in Munich, announcing that he would nonetheless issue orders for people who have already been expelled to be turned back at the borders.

"This is not about winning time or anything like that but rather that in July, if there is no result at European level, we must implement this - that is a question for the functioning of our constitutional state," he added.

Germany's migration row mirrors squalls seen across Europe since Merkel's decision in 2015 to open Germany's borders to more than a million migrants fleeing wars in the Middle East, transforming the demographic landscape almost overnight.

The CSU hopes its tough line will help it see off a challenge from the anti-immigration Alternative for Germany (AfD) party in wealthy Bavaria's October election.

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