(Reuters) -Slovakia's leftist-nationalist government on Wednesday approved a proposed overhaul of public broadcaster RTVS, which it has accused of bias, raising concerns among opposition politicians, reporters and media advocacy groups.

The legislation is the latest step in what critics say is an effort by Prime Minister Robert Fico's government to tighten control over the European Union and NATO member country.

Fico, who became prime minister for a fourth time last year after several years in opposition, has long railed against critical media and his government has refused questions from some outlets.

"The situation in RTVS is unsustainable," Fico told a broadcast news conference on Wednesday.

"(It) cannot be objectively objective because it is in dispute with the Slovak government. The basic human right for citizens of Slovakia to have objective information at their disposal is being violated."

Fico's government has already shuttered a special prosecutor's office tackling high-profile corruption, replaced heads of the police and secret service, and shifted foreign policy away from its staunch support of Ukraine.

Michal Simecka, head of Progressive Slovakia, the country's largest opposition party, said the government was using an "autocrat's handbook" with its interference in state institutions.

The European Broadcasting Union (EBU), a group of public media, said the draft legislation effectively replaced "a respected public service broadcaster" and was a threat to its independence.

Culture Minister Martina Simkovicova, who has previously worked for a media outlet known for sharing conspiracy theories, has been a critic of RTVS for failing to allow more than mainstream opinions.

Under the new legislation, expected to be approved by parliament in June, RTVS's director will be removed years before his term was to expire and a nine-member council will be responsible for filling the director position. 

The culture and finance ministries will nominate four members to the council, while the rest will be experts appointed by parliament.

Employees at RTVS, which will be renamed Slovak Television and Radio (STVR), said in a Facebook video that the legislation could become a tool for a political power grab at the broadcaster.    

The legislation approved on Wednesday tweaks proposals in the original March draft that would have created a programming board to oversee content, which critics said raised fears of censorship, and would have allowed the director to be removed without cause. 

(Reporting by Jason Hovet in Prague; Editing by Sharon Singleton, Alexandra Hudson)