Berlin looks set to hold a referendum on banning big landlords and expropriating their homes into social housing, as part of a response to growing complaints in the German capital about the cost of living.

The proposed law would bar landlords with more than 3,000 homes in their portfolio from operating in the city – including the city’s biggest property company, Deutsche Wohnen AG.

That real estate behemoth has become a favoured target of activists, who claim its business is an example of the kind of speculation which they blame for driving up rents and property values.

The expropriated homes – an estimated 200,000 would be covered – would effectively become the German equivalent of council housing, let out at social rents – in a bid to reduce the cost of living.

The city, which is its own state under Germany’s federal system, has a local constitution that provides for a system of binding ballot initiatives or Volksentscheid, which allow framework for holding referenda.

Though the initiative must first collect 20,000 signatures to make it into the ballot paper, it is likely to find them quickly, as opinion polls show a majority of voters back the plan.

The activists’ proposal has sparked extensive coverage in the German press, including legal debates about whether expropriation would be constitutional or not.

One of the activists behind the initiative told German newspaper Der Tagesspiegel that they had consulted with lawyers and constitutional experts and that the compensation for expropriations could be paid “well below the market value”.

They cite a legal precedent set by the expropriation of land in Hamburg after a 1962 flood – after which the Federal Constitutional Court ruled that the common good sometimes required property rights to be interfered with.

The left-wing Die Linke party supports the plan, as do some Greens and centre-left SPD representatives. The so-called red-red-green coalition in Berlin – made up of those three left-of-centre parties, has made building affordable housing a priority, and is also engaged in a more modest plan to buy up private housing of its own.

First pictures of the polar bear cub born in Berlin Zoo Show all 30 1 /30 First pictures of the polar bear cub born in Berlin Zoo First pictures of the polar bear cub born in Berlin Zoo The first pictures have been released of a polar bear cub that was born in Berlin's Tierpark Zoo on December 1. AP First pictures of the polar bear cub born in Berlin Zoo The pictures were taken after the cub's first veterinary examination which revealed that the 11-week old is a female. AP First pictures of the polar bear cub born in Berlin Zoo She is yet to be named and the zoo says that a name will not be announced until the cub and her mother Tonja are ready to make their first public appearance. AP First pictures of the polar bear cub born in Berlin Zoo In recent years Tonja has given birth to two other cubs, though both died in infancy. Tierpark director Dr. Andreas Knieriem says that "infant mortality in polar bears is extremely high, especially within the first ten days of life. However we are all staying positive and keeping our fingers crossed for Tonja." AP First pictures of the polar bear cub born in Berlin Zoo The pair have been living together in a birthing den where Tonja can raise her cub in privacy for the first few months. AP First pictures of the polar bear cub born in Berlin Zoo Knut Knut, a polar bear at the nearby Zoo Berlin became hugely famous in 2006 when he was rejected by his mother at birth. He was able to survive by artificial incubation and developed a close relationship with his keeper. Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut plays at the Berlin Zoo in March 2007 Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut plays at the Berlin Zoo in March 2007 Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut plays at the Berlin Zoo in March 2007 Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut rests in his den at the Berlin Zoo in March 2007 Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut in March 2007 Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut plays with his minder during his first public outing on March 23 2007 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Photographers struggle to get a view of Knut at his first public appearance on March 23 2007 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut on his first public outing on March 23 2007 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut on his first public outing on March 23 2007 Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut plays with his minder during his first public outing on March 23 2007 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut nuzzles with his minder during his first public outing on March 23 2007 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut plays with his minder during his first public outing on March 23 2007 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut in March 2007 Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut in March 2007 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut at six months old plays with his keeper on June 22 2007 Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut at 11 months old in November 2007 Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut on his first birthday on December 5 2007 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut bathes, January 2008 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut plays in hay in January 2008 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut at two years old in September 2009 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Polar bear Giovanna joins Knut in his enclosure in September 2009 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut and Giovanna, on loan from the Munich Zoo, play together in January 2010 AFP/Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut and Giovanna nuzzle in January 2010 Getty First pictures of the polar bear cub born in Berlin Zoo Knut Knut and Giovanna nuzzle in January 2010 Getty

“In addition to the new building, we also want to see how we can make a good offer in the portfolio, and this is where municipalisation plays a role,” said Berlin's SPD mayor Michael Müller in his New Year press conference last month.

In 2017 property prices in Berlin grew faster than in any other major city around the globe at 20.5 per cent, according to a ranking published last year by estate agent Knight Frank. Rents are also increasing fast, despite the imposition of new laws to control them in 2015 – in a city used to affordable and plentiful housing.