Closing Germany's borders will not solve the country's refugee crisis, Foreign Minister Frank-Walter Steinmeier said Tuesday as Chancellor Angela Merkel was struggling to quell a revolt in her coalition against her policy of keeping Germany open.

"I guarantee you that [a solution to the crisis] will not be achieved through a closure of the border," Steinmeier told foreign journalists in response to comments from Merkel's Transport Minister Alexander Dobrindt that border closures were inevitable.

Steinmeier added that a long-term solution could only be brought about through a refugee resettlement programme across the European Union, joint efforts to secure the bloc's outer borders and the fulfilment of a 3-billion-euro (3.3-billion-dollar) aid pledge to Turkey.

Steinmeier's comments come after Dobrindt told Bavarian daily Muenchner Merkur that Germany could no longer show the world a "friendly face," and that if the number of new arrivals was not reduced in the near future, Germany would not be able to avoid border closures.

Asked outright whether such a move was on the cards, Steinmeier said Germany would have to wait for the outcome of Austrian consultations on border policies before a decision is made. "We have to know what the Austrians will do," said Steinmeier.

Forty-four lawmakers from the alliance of Merkel's Christian Democrats (CDU) and its sister party, the Bavarian Christian Social Union (CSU), sent a letter to the chancellor on Tuesday decrying her stance on migration and urging a return to "the strict implementation of existing laws" - turning back those wishing to enter Germany via a safe third country.

Germany took in 1.1 million migrants in 2015, the vast majority of those to have entered Europe over the past year.