KIEV (AFP) - Ukraine's security service on Wednesday announced a nationwide "anti-terrorist" operation in response to deadly anti-government protests.

"The National Security Service and Ukrainian Anti-Terrorist Centre have taken the decision to conduct an anti-terrorist operation across the territory of Ukraine," security agency head Oleksandr Yakimenko said in a statement.

President Viktor Yanukovych has been informed of the operation that will see security agencies work with the ministry of defence to strengthen state borders and maintain public order, the statement said.

"Radical and extremist groups are posing a real threat to the lives of millions of Ukrainians with their actions," Mr Yakimenko said.

The statement said that over the past few days, some 1,500 firearms and 100,000 bullets had ended up in the hands of "criminals".