Mr Lewis, a former television executive brought in by the Government to run the prison system five months ago, said no decision had been reached on how many of the 133 jails in England and Wales would be contracted out.
But the Home Office plans are based on the assumption that about 20 existing prisons will be privatised. Any new jails will almost certainly be put out to tender as well.
If the project goes ahead, Britain will have a higher proportion of prisoners in private jails than any western country, including the United States.
This week has seen the Government acutely embarrassed by the failure of Group 4, the security firm, to hold on to inmates it was meant to transport to court after privatisation of the prison escort service in the East Midlands, Humberside and parts of Yorkshire two weeks ago. By the end of the second week, it had 'lost' seven prisoners.
But Mr Lewis showed no sign of losing faith in the ability of commercial companies.
Almost every type of prison would be offered to private firms, he told the Independent on Sunday. Only jails with secure units, for the most dangerous inmates, could be guaranteed a future in the public sector.
The aim was to create 'competition and new ideas'. All jails in the new system would have performance indicators published on their treatment of inmates. The public and the Government would then be able to see how the state and private sector met Home Office targets.
Mr Lewis said he was anxious to avoid one company having a monopoly of private jails. Between two and four firms would therefore be given management contracts and enough jails to make a 'high level of commitment of managing prisons worthwhile'.
'There are always problems in prisons and I don't want a firm to be able to throw up its hands and walk away because it does not have a big enough stake in making the system work,' he said. This means that each of the private companies will probably receive contracts for at least four jails.
At present only two jails are in the hands of private managers: the Wolds in Humberside, which is run by Group 4, and Blakenhurst in Hereford and Worcester, which will be managed by UK Detention Services when it opens next month. Strangeways in Manchester is the only other prison out for tender at present. Its management has submitted an internal bid.
Mr Lewis hinted that in-house bids by Home Office staff might be banned in future, but added that he had no objection to prison managers leaving to help run the private sector.
The list of the new wave of jails to be put out to tender will be completed in the summer. They will be in the private sector by 1995 or 1996. US security companies, such as Pricor, are moving into Britain hoping for contracts.
Mr Lewis said he thought the state prison service would benefit. 'I hope different operators with different angles will break up a monolithic and monopolistic organisation which has not consistently achieved high standards,' he said. 'I hope the competition will invigorate the public sector. If it does not, then we will look at extending private management.'Reuse content