Companies exploiting workers through outsourcing contracts are among the visitors to the Labour Party’s annual conference, a union leader has claimed.

Mick Lynch, general secretary of the Rail, Maritime and Transport union (RMT), called on an incoming Labour government to tackle outsourcing, which he said “degraded” workers.

He told a fringe meeting at the Liverpool conference that workers employed on contracts which had been outsourced to private firms were on the lowest wages in the country.

They included black workers and migrants working in jobs such as cleaners, he said.

“They are being exploited by people who are in this conference this week.

“They have to be called out.”