More than 700 prison guards whose jobs are considered non-essential are on strike across the country. They're defying a back-to-work order passed this week in Ottawa.

The Public Service Alliance of Canada guards are blocking entrances to several federal penitentiaries in Ontario and British Columbia.

The federal government has the option of ordering the guards back under the legislation but it still hopes to negotiate a contract with the guards. The guards haven't yet received the orders to return to work.

The prison guards haven't had a raise in seven years and are pushing for wage parity with the RCMP. The guards' union says their salaries are 32 per cent less than that of the RCMP.

Corrections Canada assures that essential service levels are in place at all the institutions. Most of Canada's 4,500 federal prison guards are not allowed to strike, but about 700 are considered non-essential workers.