Chinese citizens are guaranteed freedom of speech by the nation's Constitution, Zhang Jun, vice-president of the Supreme People's Court, said on Saturday.

"Citizens have the rights to express their ideas under the legal system, which includes suggestions to and criticisms of the government. These rights are protected by law and by the Constitution," Zhang said.

It is acceptable for people to criticize preparations for the Olympic Games or express their complaints, he added.

Zhang made the remarks in response to questions raised by foreign media at a press conference on the sidelines of the ongoing legislative session.

But Zhang added: "Freedom of speech does not mean you won't face punishment for slandering and insulting other people."

If the circumstances are serious enough to constitute a crime, those responsible shall be prosecuted, Zhang added.

At the same press conference, senior prosecutors said Chinese judiciary bodies had brought more than 70 criminal suspects back to China from more than 30 countries and regions since 1998, achieving "good results" in catching corrupt officials who had escaped overseas.

"China has been active in seeking international cooperation in its fight against corruption," said Jiang Wei, president of Northeast China's Heilongjiang provincial high people's procuratorate.

The country has become one of the strongest supporters of the United Nations Anti-Corruption Convention.

The official said China has established an international mutual assistance mechanism to pursue corrupt officials who have fled the country.