Newly appointed Czech Prime Minister Andrej Babis speaks to media at Prague Castle in Prague, Czech Republic, June 6, 2018. REUTERS/David W Cerny

PRAGUE (Reuters) - Czech Prime Minister Andrej Babis, re-appointed to office on Wednesday, said that he would sue Slovakia in the European Court of Human Rights over allegations that he had been an informer for the Communist-era secret police.

A Slovak court last February rejected a demand by the Slovak-born Babis to be cleared of colluding with the branch of then Czechoslovak police (StB) which the then communist rulers used to control society.

Earlier on Wednesday, the Czech president re-appointed the billionaire businessman as prime minister, endorsing a coalition-in-waiting that will give the anti-NATO Communists a say in policymaking for the first time since the 1989 revolution that ended communist rule in then Czechoslovakia.

Babis, 63, a member of the Communist party before 1989, said he would defend himself against the charges of collusion with the StB which are based on state historical archives.

“I understand that people don’t like me. They are influenced by the hundred-times repeated lies. I will sue Slovakia by June 15 at the European Court for Human Rights,” he told reporters on Wednesday.

Babis has admitted to meetings with StB officers in the 1980s in the former Czechoslovakia when he was a Communist Party member and worked in foreign trade, but he insists he only discussed the country’s economic interests.

The prospect of Communists getting a share of power again sparked another wave of protests on Tuesday, bringing thousands of people to the streets.