Iraqi police say at least 30 people were killed and more than 20 others wounded when a suicide bomber blew himself up on a bus in Baghdad on Thursday.
Witnesses say the attacker boarded the bus just as it was about to leave for Nasiriyah -- a Shi'ite city some 320-kilometers south of Baghdad.
Separately, an American soldier was killed when his convoy hit a roadside bomb in an eastern part of the Iraqi capital.
Meanwhile, Arabic broadcaster al-Jazeera reports that insurgents holding four Western hostages have extended until Saturday a deadline to kill them unless Iraqi prisoners are freed. The original deadline was Thursday.
In London, British Foreign Secretary Jack Straw appealed again on Thursday for the release of the Western peace campaigners.