B.C.'s fruit growers are being warned that so-called radical labour activists may try to trespass on their farms this summer and impersonate government officials.

"These activists wish to identify and even create problems with SAWP workers on your farm," the B.C. Fruit Growers' Association said in a May 11 newsletter to its members.

SAWP refers to the Season Agricultural Worker Program, which employs temporary foreign workers from Mexico and the Caribbean for up to eight months. B.C. took on nearly 7,000 workers in 2015.

The letter says that all unknown visitors should be asked to present ID and that workers should ask their employers for permission before speaking to visitors during working hours.

It says workers can have guests during non-working hours, but that those guests must still sign in.

Concerns with food safety

Glen Lucas, the BCFGA's general manager, said the letter was sent to members after a recent meeting where Fraser Valley activists said they had been visiting farms in the Okanagan.

"That's a concern in several ways," Lucas said on CBC's Daybreak South. "Mainly to do with food safety and bio security, but also interfering with the workplace."

There are no reports of activists impersonating government officials. But Lucas said an activist group in the Fraser Valley has received contract funding from the federal government.

He said the BCFGA fears that those activists could falsely claim to be representing the government.

"We wanted to address that concern before it happened."

'Alarmist' letter

A spokesperson with Radical Action with Migrants in Agriculture, a grassroots advocacy group for the 1,200 Latin American and Caribbean migrant workers in the Okanagan, said the group was "perplexed" by the letter.

"It certainly seemed to be quite alarmist," Christine Mettler said.

"From what we could tell, there was scant evidence to support some of those claims."

Mettler said its members don't need permission to visit workers on the farm, since the workers pay rent to live there.

"These are tenants," she said. "I also visit my friends who are renting without the landlords' permission."

Critics of the seasonal-worker program say that migrants don't get the same workplace protections as Canadians.

Workers who speak out about low wages or poor working conditions risk being sent back home, Mettler said.

She said that cutting off workers from support groups will only isolate them further.

With files from CBC's Daybreak South