West Sussex Police, accompanied by investigators for the Gangmasters Licensing Authority (GLA), yesterday made four arrests in Portsmouth and West Sussex in connection with migrant workers employed in farms and horticultural nurseries in the region.

Three residential addresses and two offices – in Portsmouth and Havant – were raided, and those arrested remain in police custody.

Officers and GLA staff have visited nurseries across West Sussex – in Ferring, Chidham, Walberton, Angmering and Funtington – to talk to staff. No arrests were made.

According to its annual report 2010-11, the GLA identified 845 workers whose exploitation in total valued nearly £2.5m, with 12 prosecutions resulting from investigations.