Ms Villiers told the House of Commons 66 police officers had been injured since violence first flared up following the decision to restrict the flying of the union flag at Belfast City Hall.
The war of words flared as Royal Mail boss Adam Crozier rubbished the main postal workers' union's suggestion that the firm treats its staff as "slaves".
Greece is at the forefront of the most recent problems as concerns flared that it would not receive its next tranche of payments from the International Monetary Fund and the European Union.