The Northern Ireland police ombudsman is to probe claims that security forces in Northern Ireland had prior knowledge of the Omagh bomb.

A former special branch agent, known as Kevin Fulton, claims the security forces had intelligence warning of a bomb "days before" the blast which killed 29 people.

Senior security officials have vehemently denied the claims that they knew of the attack more than 48-hours before the device was planted.

Families of those killed in the blast have welcomed the announcement of an inquiry.