Michael Bloomberg used prisoners to make campaign calls

US presidential candidate Michael Bloomberg has said that his campaign "did not know" they were contracted with a company that uses prison labor for outside services.

Mr. Bloomberg stated that he cut ties with the vendor which runs two call centers in the state-run prison system. He said he was unaware that his campaign was using such a vendor until he received a call from a reporter.

The former mayor of New York City and billionaire businessman through his hat into the presidential race in November with one of the largest ever advertising buys.

His use of prison labor was first published by the news site “The Intercept” and Mr.Bloomberg also confirmed it in a statement released on Tuesday, December 23. In his statement, Mr. Bloomberg stated that we do not support this practice and are making sure our vendors are properly vetted moving forward.

According to The Intercept, Mr. Bloomberg - using a third-party vendor - hired call center company ProCom to make phone calls for his campaign.

The firm operates two centers in Oklahoma state prisons. An unidentified source told The Intercept that incarcerated people were contracted to make calls from at least one of these prisons - a minimum-security women's prison with a capacity of over 900 inmates.

Matt Elliott, a spokesman for the Oklahoma Department of Corrections, told CBS News that inmates could earn up to $1.45 an hour working for call centers. "We believe this type of work helps prepare inmates for release," he said.