A new law against dodgy business operators has come into force, obliging all companies to trade fairly.

The move outlaws practices such as false closing-down sales to misleading claims by salespeople, specifically banning 31 practices.

The National Consumer Council said groups had been campaigning for such a law for 20 years and welcomed its eventual introduction.

"These new laws represent a big boost to consumer protection, particularly for vulnerable people who are targeted by rogue traders," said the organisation's Carl Belgrove.

But the new rules stop short of allowing customers to claim compensation from a company that treats them unfairly.