AFP BERLIN GERMAN Chancellor Angela Merkel and Turkish Prime Minister Recep Tayyip Erdogan on Wednesday marked 50 years since their countries’ first “guest worker” pact with calls to deepen their political and cultural ties.

When Turkish migrant workers first arrived to work in Germany’s car plants, coal mines and steel foundries half a century ago to fill a yawning gap in the booming country’s workforce, most Germans thought they would soon be gone.

Today, some three million Turks or Germans of Turkish origin are settled in this 82- million-strong country, representing its largest ethnic minority.

At a ceremony with Erdogan as guest of honour, Merkel said Turks had long become an integral part of German society but lamented a persistent lag in education levels and German fluency that she said was hobbling full integration.

These problems must not be swept under the carpet,” she said.

Erdogan said Turks were now “an integral part of German society” and cited the accomplishments of footballer Mesut Ozil and filmmaker Fatih Akin as examples of the contributions those of Turkish extraction made in Germany that should be recognised.

He said that for this reason, Berlin should strongly back Ankara’s drive to join the European Union.

“We would hope that Germany would be doing the most to push for Turkish membership of the EU,” he said.

Berlin favours a “privileged partnership” between the EU and Turkey, an alliance which would fall short of full membership.

Erdogan also said Germany must do more to fight “terrorist organisations” on German soil, in a reference to groups linked to the Kurdistan Workers’ Party (PKK) — an accusation Merkel rebuffed.

“We stand firmly by your side when it comes to the fight against terrorism with no ifs, ands or buts,” she said. Some 900,000 Turks arrived between 1961, when the Turkish-German labour exchange pact was signed, and 1973 when the oil crisis and rising unemployment put paid to it, according to the German migration centre (DOMiD).

At first the “guests” — 20 percent of them women — signed up for two-year contracts.

But in 1964, the rules were relaxed to allow employers to decide how long contracts would run.

While Germany called it a “guest worker” programme and long resisted the notion that it had become a “country of immigration,” the legacy of the pact has irreversibly transformed German society.

However Merkel and other officials regularly complain that many Turks have proved unwilling, or unable, to make the most of their lives here by failing to master German or fully adopt the culture’s norms.

This has sometimes fuelled tensions, with a former central banker publishing a runaway bestseller last year saying Germany was being made “more stupid” by four million purportedly undereducated and unproductive Muslim migrants.

Some 30 percent of students of Turkish origin do not have a school leaving certificate, and just 14 percent pass their final secondary school examinations, according to a study by the Berlin Institute for Population and Development.