US media say investigators have uncovered images of a suspect who may have planted the Boston Marathon bombs. However, officials have denied earlier media reports that a suspect had been questioned.
An anonymous US law enforcement source said Wednesday that police believed they had identified a suspect in the Boston Marathon bombing investigation.
Investigators viewing video footage had identified a man leaving a bag close to where one of the explosions took place and walking away.
In a statement, however, the Federal Bureau of Investigation (FBI) and the US attorney's office in Boston said no arrests have been made, despite earlier reports that a suspect was being held in custody.
"Contrary to widespread reporting, there have been no arrests made in connection with the Boston Marathon attack," the FBI said.
An official news briefing on the latest developments was expected later on Wednesday.
Since Monday's fatal bombing, the FBI said it had conducted a "worldwide" hunt for the perpetrators of the attack, which killed three people and injured more than 170. That search had led investigators to comb the area for clues, with suspected bomb parts found on the roofs of buildings close to the scene.
Images released by the FBI late on Tuesday showed what appeared to be a mangled pressure cooker and black bag at the scene of the Boston bombings.
Metal pellets and nails
Richard DesLauriers, FBI agent in charge in Boston said fragments of suspected pressure cookers thought to have been used to pack the bomb were being put together by experts. He added that metal pellets and nails had also been recovered.
US President Barack Obama has announced he will attend a special service Thursday for those killed and injured in the twin-bombings near the finish line of the Boston Marathon on Monday.
The victims have been identified as eight-year-old Martin Richard and Krystle Campbell, 29, a restaurant manager from Massachusetts. According to China's Xinhua news agency the third victim was a Chinese national believed to be a graduate student at Boston University. Her name has not yet been given.
More than 1,000 people attended a candle-lit vigil for Martin Richard near his family home in the Boston suburb of Dorchester on Tuesday. Hundreds more attended another vigil in central Boston and a church service near the scene of the blasts.
ccp/rc (AFP, dpa, Reuters)