LONDON, June 29 (Reuters) - Britain's government is to appoint a retired judge on Thursday to lead a public inquiry into the devastating fire in a London tower block of apartments that killed at least 80 people, a spokesman said.

Prime Minister Theresa May promised to hold the inquiry into the fire a day after it broke out in Grenfell Tower in the early hours of June 14, gutting the 24-storey block and trapping residents in their beds as they slept.

A spokesman for May's office said retired court of appeals judge Martin Moore-Bick would be appointed later on Thursday to head the inquiry. Moore-Bick spent more than 20 years as a judge and retired in December last year from his role as Lord Justice of Appeal.

The Times newspaper said members of May's senior team had expressed initial misgivings about Moore-Bick after he ruled in favour of a London council in a dispute with a single mother of five children who had refused to be rehoused away from her home into a city north of London.

The ruling was overturned by the Supreme Court.

Families who survived the blaze at the Grenfell social housing block have expressed concerns that they will be rehoused away from the Kensington area in London.

Police have said that at least 80 people were dead, or missing and presumed dead, from the fire. The final death toll will be known only after officers complete a painstaking search and recovery operation which could take until the end of the year.

(Reporting by Sarah Mills; Editing by Richard Balmforth)