Germany toughened its rhetoric yesterday in response to an accelerating influx of asylum seekers, pledging to step up deportations of migrants and accusing its neighbour Austria of trying to push refugees over the border after dark.

The sharper tone from Interior Minister Thomas de Maiziere came as a new poll showed support for Chancellor Angela Merkel’s conservatives slumping to a three-year low over her handling of the refugee crisis.

She has been pummelled by her conservative allies in Bavaria, the southern state where most migrants are entering Germany from Austria, for refusing to commit to measures to stem the tide.

Yesterday, Germany’s top-selling newspaper Bild reported that Horst Seehofer, the Premier of Bavaria and head of the Christian Social Union (CSU), was considering pulling his party’s three ministers out of Ms Merkel’s Cabinet in Berlin in protest at her policies.

Although Mr Seehofer has delivered a series of ultimatums in recent weeks that he has not followed through on, the report underscored how serious tensions within the federal government have become as hundreds of thousands of migrants, mainly from Syria and Afghanistan, stream into Germany.

Ms Merkel has argued that the crisis can only be solved by tackling its root causes: the war in Syria and poor conditions for refugees in countries like Lebanon, Jordan and Turkey.

In the face of rising criticism and declining poll numbers, she has stuck doggedly to her mantra “we can do this”. But the tougher rhetoric yesterday pointed to a shift in tone that may be aimed at containing the political damage.

Merkel’s conservatives slump to a three-year low over her handling of the refugee crisis

Mr De Maiziere acknowledged at a news conference that the influx had accelerated strongly in recent days due to a backlog of migrants travelling through the Balkans.

“I expect that in the coming weeks, the number of deportations and of voluntary departures will rise significantly,” he said.

He described a sharp rise in the number of migrants coming from Afghanistan as “unacceptable” and said talks had been held with the government in Kabul to put a halt to it, saying Afghans should “stay in their country”.

However, his most pointed rhetoric was reserved for Austria, whose recent handling of refugees he called “out of order”.

“We observed that refugees, without warning and after dark, were being driven to the German border without any provisions or forethought,” Mr de Maiziere said yesterday.

For its part, Austria yesterday outlined plans to build barriers including a fence at a busy crossing on its southern border with Slovenia to slow the influx of transiting migrants.

Meanwhile, a new poll from Forsa yesterday showed Ms Merkel’s conservatives dipping two points to 36 per cent, their lowest level in three years, compared to 24 per cent for the SPD.