Masked gunmen last night carried out an attack on the office of anti-mass migration Bundestag member Bettina Kudla in Leipzig, a police spokeswoman has confirmed.

A sinister message claiming responsibility for the office break-in was posted on the far left Indymedia website. Accusing Ms. Kudla’s Christian Democratic Union (CDU) party of the “mass murder” of migrants in the Mediterranean, it threatened “Germans will always have to pay the price”.

Overnight, four windows of Ms. Kudla’s office were smashed and 40 square metres of the building’s exterior, along with three cars parked outside, was smeared with a black, tar-like substance.

A witness who observed the attack said there were three perpetrators, all masked, and that one of the vandals was wearing a helmet. The CDU politician’s office was previously trashed by criminals in August.

Ms. Kudla recently came under fire for using the word “Umvolkung”, a term critics linked to Nazi Germany. Meaning “ethnicity inversion”, it refers to the forced ethnic transformation of a population and has recently been used by right wingers criticising mass migration.

The statement posted on Indymedia, which claims responsibility for the attack, slams the idea of a demographic transformation of Germany as “a myth”. It was revealed last month that 40 per cent of children under 5 in Germany now have a migrant background.

The post argues that by discussing the concept of population replacement, Ms Kudla is “providing legitimacy to the murderous thirst of fascists on the streets”.

It criticises the centre-right CDU and the centre-left Social Democratic Party for tightening asylum rules and blamed them for “mass murder in the Mediterranean”, presumably referring to migrants who have drowned illegally trying to enter Europe.

The post also slams German Unity Day celebrations for “celebrating the myth that… racists and neo-Nazis don’t belong to Europe”. Claiming that Germans are responsible for migrant deaths and “the impoverishment of Europe” its anonymous authors warn, “for that, they will always have to pay the price”.

The vandalism comes after a series of attacks on offices, vehicles and election posters of the anti-mass migration and eurosceptic Alternative for Germany party, support for which has risen to double-digits.

Earlier this year a study by the Berlin Senate’s Department of Internal Affairs found that far-left activists are increasingly targeting individuals in their attacks, with strategies including subjecting conservative residents to abuse and physical assaults.