The Czech government stepped up security measures in Prague on Saturday because of the "most serious" information about a terrorist threat, the interior minister said.
The government received information about an increased danger of a terrorist attack in Prague, and security was stepped up at dozens of locations in the capital, including the Ruzyne international airport, Interior Minister Ivan Langer told a news conference.
"The information ... was evaluated as serious, the most serious ever," Langer said.
Langer refused to provide any further information about the threat, but according to police chief Ladislav Husak, locations that normally are not guarded were among possible targets.
Police spokeswoman Eva Miklikova said police searched a busy bridge after an anonymous caller said a bomb was planted there, but no bomb was found.
A spokesman for the country's counterintelligence service - the BIS - suggested separately that the Czech Republic's support for the United States in Iraq and Washington has increased the threat of terror attacks in the central European country.