Time is running out for labour providers to register with the Gangmaster Licensing Authority, chief executive Mike Wilson has warned.

The deadline for gangmasters to apply to the GLA is 1 September, but numbers registered so far still fall far below targets. Last week, the GLA reported that more than 280 out of the 1,000 key labour providers had not been in touch.

To date, only 473 licences have been issued, the majority on the condition that the licensee makes key improvements in time for a further inspection later this year.

Wilson said that the figures suggested almost 300 businesses could be operating illegally by 1 October, when sanctions against unregistered providers come into force.

"It will be illegal to operate as a labour provider in the affected areas without a GLA licence after 1 October. And if insufficient labour providers are licensed by this time, the industry will incur difficulty," he said.

"The simple solution is for labour providers to get themselves licensed. If ­everybody is licensed in time there will be little effect on the industry except that standards will have risen and exploitation fallen. If labour providers are not licensed, this could lead in the worst-case ­scenario to production and supply problems in the food industry."

But GLA chairman Paul Whitehouse said another 80 applications were part-finished on 21 August and dismissed fears that would lead to a mass of unlicensed labour this autumn.

"One thousand is the number of labour providers we think are out there, but that's not to say, if we get fewer, it's because we've missed them. It is just an estimate. We've always assumed there would be a last-minute rush, not least because the licence runs from the day it is issued."