UK ports will get new powers to block ferries from docking if they do not pay their crew the minimum wage.
Transport Secretary Grant Shapps said the move was a warning to P&O Ferries - after the firm's no-notice sackings of 800 staff to replace them with cheaper agency workers - that "the game is up".
"This will send a clear message to the maritime industry: we will not allow this to happen again," he told the Commons.
