PRAGUE — The Czech Senate approved a motion to file treason charges against President Vaclav Klaus over an amnesty he granted to thousands of convicted criminals and suspects at the start of the year.

The upper house of parliament, controlled by the opposition Social Democrats, approved the request in a ballot Monday, Senate head Milan Stech told reporters in Prague. The charge will be filed at the Constitutional Court, Stech said.

The Social Democrats, the most popular party in opinion polls and the largest in both houses of the legislature, has criticized the amnesty and last month initiated a no-confidence vote against the government over the president’s move. Klaus has said the amnesty was legal.

“The Senate couldn’t remain silent in a situation when the president repeatedly violated the constitution,” Jiri Dienstbier, a Social Democratic senator, said in a televised briefing. “The independent Constitutional Court will have a chance to assess how deep the violation of the constitution by the president was.”

Klaus, the Czech Republic’s highest-profile critic of the European Union and its common currency, will leave office on March 7 when his second and final term expires. Among his most notable acts during 10 years as president was to delay signing the EU’s Lisbon Treaty in 2009.

According to the constitution, presidents found guilty of treason must step down and cannot hold the office again.