The Abbott government has given Transfield Services a $1.22 billion government contract to run immigration detention centres on Nauru and Manus Island.

Shares in Transfield soared 20.8 per cent on the news, reaching 96¢ by 12.34pm, lifting the company's market capitalisation by about $80 million.

Tents at the detention centre on Manus Island. Credit:Jason South

Transfield, which was until October chaired by Tony Shepherd, who is heading the government's Commission of Audit, announced the size of the deal to the ASX on Monday morning.

The deal runs for 20 months and covers ''garrison and welfare services'', the company said.