Investigators are looking into whether embattled New Jersey Governor Chris Christie misused about $2m (€1.5m) in Superstorm Sandy relief funds for an ad campaign that put him in the spotlight in an election year, a politician has said.

New Jersey governor Chris Christie yesterday apologised to his constituents and said he was “embarrassed and humiliated” by his staff but had no idea his aides may have closed highway lanes to exact political retribution.