The Czech Republic's ruling party might consider forming a government with the Communist Party (KSCM) next year, the prime minister told a newspaper, contemplating an alliance that would break a 27-year-old taboo.

 

Bohuslav Sobotka told daily Hospodarske Noviny his Social Democrats did not rule out joining forces with the KSCM after national elections due by October 2017.

 

He made the prospect conditional on the Communists dropping their anti-EU agenda and opposition to the NATO military alliance - a policy cornerstone of the party that ruled the country from 1948 until the Iron Curtain fell in 1989, when it was a satellite state of the Soviet Union.

 

"I can imagine cooperation with the Communists on the basis of clear boundaries concerning the security of the Czech Republic, mainly not doubting NATO membership and a pro-European government stance," Sobotka said.

 

While the Communists have given no indication they would consider meeting such conditions, the prime minister's comment suggests a softening of a broad-based opposition to giving the party a place in a democratically elected government.

 

It may also reflect the state of opinion polls.

 

The latest, a CVVM institute survey from September, showed the Social Democrats on 23 percent, lagging their current main coalition partner - the centrist ANO party - on 28.5 percent, with the Communists third with 15 percent.

 

The Communists have been part of several regional governments but remain a pariah for other parties at national level given the country's totalitarian past and their foreign policy views, including support for Russia.

 

Sobotka said his party was ready to cooperate further with the Communists at regional level, ahead of regional elections taking place on Friday and Saturday.

 

The Czech Republic joined NATO in 1999 and its government has kept its distance from Russia at a time when KSCM lawmakers have made frequent visits to separatist regions of eastern Ukraine.

 

Sobotka's Social Democrats joined forces with the ANO, led by billionaire businessman Andrej Babis, and the centrist Christian Democrats after national elections in 2013.

 

Babis and Sobotka have pledged to keep their alliance together until the next election, but the start of a new campaign cycle has revealed wide cracks as the two parties battle for leadership of the next government.

 

Babis, who runs a conglomerate that is the biggest private employer in the country, upended traditional party politics with the rise of his ANO movement in 2011. His critics accuse him of conflicts of interest.