A bill allowing the detention of terrorist suspects for up to 30 days without a court order -- an increase from 10 days -- passed its second reading in the State Duma on Friday.

The bill's sponsor, United Russia Deputy Gennady Raikov, said Monday that the extra detention time could help investigators find evidence to file charges in complicated cases that involve terrorist chains.

Under the previous rules, police often have to release suspects before they are able to charge them, Raikov said.

Vladimir Vasilyev, the head of the Duma's security committee, said the 10-day limit was too short for operatives working in the field or when an investigation includes sophisticated studies by experts, Gazeta reported.

The longer detention period would apply to people suspected of crimes that fall under nine separate articles of the Criminal Code, including those covering terrorism, hostage-taking, organization of an illegal armed formation, banditry, attempt on the life of a statesman or public figure, coup, armed rebellion, subversion and attacks on people or offices under international protection.

The bill would amend two articles of the Criminal Procedures Code, Nos. 97 and 100.

The Duma is expected to give the bill its final reading next week, Raikov said.