Angela Merkel has called for a burqa ban in Germany as she stands for her fourth consecutive term as Chancellor.

The German leader told her conservative Christian Democratic Union (CDU) on Tuesday that she would support a nationwide prohibition on the Islamic full face covering. 

"The full-face veil must be banned, wherever it is legally possible," she said to enthusiatic applause from party delegates in Essen. "German law takes precedence over sharia."

She also said the refugee crisis "must never be repeated" in a speech to mark her unopposed pitch to be the party's candidate.

It comes after her close ally and Germany's interior minister Thomas de Maiziere backed a partial ban in August. He suggested a law could apply in "places where it is necessary for our society's coexistence" such as government offices, schools, courtroom and demonstrations.

"We all reject the full veil – not only the burka but also other types of full veil that only leave the eyes visible. They have no place in our society," Maiziere said at the time.

"Showing your face is essential for our communication, co-existence and social cohesion and that's why we're asking everyone to show their faces," he added. "We want to introduce a law to make people show their faces and that means that those who break that law will have to face the consequences." 

If Germany goes ahead with the proposal it will be the latest in a list of European countries following France's controversial ban in 2011. Since then Belgium, Bulgaria and parts of Switzerland have fined those wearing the veil in public.

Dutch MP s voted for a similar ban in the Netherlands last month as support for similar legislation increases in Europe.

Merkel is fighting a slump in her popularity after she opened Germany's borders in September 2015. She has refused to back down despite intense criticism that the influx overwhelmed public services and left refugees in under-equipped camps.

But Tuesday's speech marks a distinct change in tone after the far-right Alternative for Germany (AfD) won support with attacks on Merkel's immigration stance. The popularist party supports a total ban on burqas.

"A situation like the one in the late summer of 2015 cannot, should not and must not be repeated," Merkel said of the migrant crisis. "That was and is our, and my, declared political aim."