PAYDAY lender Wonga.com has been criticised by the trading watchdog for using aggressive and misleading debt collection methods.

Wonga suggested in letters and emails, without appropriate justification, that some customers may have committed fraud, the Office of Fair Trading (OFT) said.

Several hundred letters went out to customers who had asked their card providers to reverse a payment made to Wonga and to those who had entered into debt management plans, the OFT said.

The watchdog said the high-profile lender told customers it would consider contacting police if they did not do as Wonga asked in the letters, which were sent out more than 18 months ago.

The OFT has imposed a requirement on Wonga, under the Consumer Credit Act, saying that it must not allege customers have or may have engaged in criminal conduct, without the necessary justification.

The watchdog also said Wonga must not tell customers they should not be in debt because of the job they hold or for any other reason, after finding a Wonga call script saying customers who work in the public or financial sectors should not go into debt.

The measures mean if it behaves in that way again, Wonga could face fines of up to £50,000.

Wonga said it planned to appeal against the OFT's decision.

It said the letters were sent on "isolated" occasions and it had already put a stop to such activities.