Angela Merkel urges Turkey to ensure freedom of expression ahead of referendum giving President Erdogan greater power

Erdogan accuses Germany of behaving 'like Nazis' after Turks banned from political rallies

Angela Merkel warned Recep Tayyip Erdogan, the Turkish president, against any attack on free speech or democracy on Thursday as she sought to shore up the fragile European alliance with Turkey.

“Opposition is part of democracy. We see that with one another every day in democratic states,” Mrs Merkel told Mr Erdogan on a visit to Ankara.

Mr Erdogan has come under international criticism for his crackdown on the Turkish opposition since last year’s failed coup attempt.

In a referendum in two months time he is to seek wide-ranging new execuitive powers critics say could endanger democracy in Turkey.

“At a time of such deep political change, everything must be done to preserve the separation of powers, and above all freedom of opinion and the plurality of society,” Mrs Merkel said.

“During the coup, we saw how the Turkish people stood up for democracy and for the rules of democracy.”

Speaking in Nato’s largest Muslim majority member, Mrs Merkel also hit out at Donald Trump’s Muslim travel ban.

“The fight against terrorism does not justify general suspicion of Muslims,” she said.

But the tensions in Europe’s relations with Nato’s largest Muslim-majority were on display at a testy joint press conference with Mr Erdogan.

In a sign of potential clashes ahead for Mr Trump, the Turkish leader bridled when Mrs Merkel referred to “Islamist terror”.

“Personally, as a Muslim, as a Muslim president, I can never accept this,” he said.

The visit was a tight rope walk for Mrs Merkel, who wants to protect the EU’s migrant deal with Turkey, which she helped broker, and keep Mr Erdogan on board as an ally.

Profile | Recep Tayyip Erdoğan

But critics accused her of lending legitimacy to his regime ahead of the controversial referendum.

Mrs Merkel is also facing growing pressure at home from her challenger in September’s elections, Martin Schulz, the former European parliament president and outspoken Brexit critic.

An opnion poll for German television released on Thursday found support for Mr Schulz’s Social Democratic Party (SPD) has risen eight points since he took over as leader.

The party is now on 28 per cent, within touching distance of Mrs Merkel’s Christian Democratic Union (CDU), which fell three points to 34 per cent.

More worrying for Mrs Merkel, the poll found that if there were a direct election for chancellor, Mr Schulz would win by a big magrin.

Half of Germans would vote for him, compared to just 34 per cent for Mrs Merkel.

Profile | Angela Merkel