New York  - Presidential candidates Barack Obama and John McCain cast aside politics on Thursday to pay their respects to the victims of the September 11 terrorist attacks, appearing together at the former site of the World Trade Center in New York.

Democrat Obama and Republican McCain shook hands and quietly chatted as the walked down the ramp leading to "Ground Zero," where ceremonies had taken place to mark the seventh anniversary of the attacks that killed nearly 3,000 people.

Obama and McCain were followed by McCain's wife, Cindy, and New York Mayor Michael Bloomberg. The two men each laid a flower in the memorial reflective pool, where hundreds had been placed earlier Thursday by the victims' families.

The candidates also greeted onlookers and local police officers, thanking them for their service. The joint, 20-minute gathering was a brief reprieve from a campaign that has grown increasingly nasty in recent weeks as the November 4 election approaches.

Obama, 47, and McCain, 72, have exchanged barbs over who will better defend US interests abroad. Obama has sought to tie McCain to President George W Bush's policies in Iraq, while McCain has called Obama's plans to set withdrawal timelines for US troops "irresponsible." (dpa)