BOSSES are still imposing “exclusivity clauses” on zero-hours contract workers even though the practice was banned months ago, a Labour member of the London Assembly revealed today.

Employers are using “effective exclusivity clauses” to penalise workers for accepting or looking for extra work elsewhere, despite the ban coming into force in May, according to Fiona Twycross.

The threat of being “sacked” or having hours slashed looms over workers if they take on other jobs or raise grievances with managers, even when a clause is not written out in a contract.

At least 96,000 workers on zero-hours contracts in London should be guaranteed 80 per cent of hours worked over three previous months, said Dr Twycross — who is launching a report called Zero Sum Game into the use of zero-hours contracts in the capital.

McDonald’s in New Zealand has recently agreed to guarantee hours in a promise to trade unions.

She added: “With London’s cost of living so high, guaranteeing a minimum number of hours would help tackle the overwhelming insecurity that comes with not knowing when your next pay cheque will arrive.”