President Barack Obama on Sunday tied himself to Martin Luther King's pursuit of justice and equality in America, as he dedicated a monument erected in memory of slain the civil rights leader in Washington.

In overtly political passages, Mr Obama sent a message to his beleaguered supporters not to give up and that King's struggle remained unfinished as election year approaches.

The 30ft high pink granite monument to King is the first dedicated to a black American, and the first to a non-president or non-war hero on the National Mall, the capital's hallowed central park.

Fifteen years in the making, its designers could not have predicted then that the monument would be dedicated by the nation's first black president, just as in the heady days after Mr Obama's election it could scarcely have been predicted that he would face such bleak re-election prospects now....