The Church of England’s asset manager has warned fast-food giant McDonald’s it may divest its £89m stake unless the company improves its response to modern slavery concerns.

CCLA Investment Management, which oversees £3.4bn in assets for thousands of charities and Church of England bodies, has criticised the burger chain after it emerged that trafficked workers from the Czech Republic were exploited in a Cambridgeshire McDonald’s franchise.

Victims were forced to work long hours, threatened regularly, and had their wages taken by gang members. Several perpetrators were jailed in December last year.

Dame Sara Thornton, CCLA’s director for modern slavery and former anti-slavery commissioner, said McDonald’s handling of the situation had been inadequate.

Writing in The Times, she said: "The company’s response to the findings of worker exploitation had been poor."

While McDonald’s UK chief executive described the case as the work of an infiltrating gang, Thornton said: "It was the workers who were the victims, not McDonald’s."

She added: "If they fail to engage, we may reconsider our investment. All options are on the table."

In response, McDonald’s said it condemned the crimes and praised the victims’ bravery during legal proceedings.

The company said it was working with the anti-slavery charity Unseen and had strengthened systems to detect exploitation.

"We will play our part...to help combat the evils of modern slavery," a spokesperson said.