Robert Tchenguiz turns his attention towards Luminar

Over the past week, Mintgate Investments has built a stake of just under 6 per cent in Luminar, which listed in London in 1996 with a market value of around £30m. Luminar's main brands are Chicago Rock Café, Oceana and Jumpin' Jaks.

Mintgate is co-owned by Mr Tchenguiz, an Iranian property tycoon, Prestbury Investment Holdings, run by the young property entrepreneur Mr Leslau, and West Coast Capital, run by Mr Hunter, a Scottish retail entrepreneur. Sources stressed the group's plans were still at a very early stage and that a bid, if one is made, was still some way off. Mr Leslau said: "We like the company. We rate [the chief executive] Steve Thomas very highly."

Luminar said it had not received any approach for the business and that it was not in talks with Mintgate or any other party.

Analysts said Luminar was an attractive target, particularly for private-equity investors. Nigel Parson, at Williams de Broë, said: "There is a lot of business and balance sheet restructuring to be done that would benefit from being away from the public eye but, once complete, the price is a compact, good quality, highly cash generative company."

But Mr Parson said Mintgate might have to offer up to 780p a share to clinch a deal. Mr Tchenguiz said on Monday he was in talks with a number of parties about a possible bid for Mitchells & Butler, which runs about 2,000 managed outlets such as All Bar One, O'Neills and Harvester restaurants.

In December, Mr Tchenguiz, who owns 800 pubs in Britain, narrowly lost out in a deal to buy the Spirit pubs group and its 1,832 managed pubs, which was sold by its private-equity owners to Punch Taverns for £2.68bn.

Luminar is run by Stephen Thomas, the Welshman known as the "king of disco". Since its peak three years ago, when it had more than 300 venues, Luminar has been hit by the mushrooming of new bars on the high street. The resulting price war, combined with rising staff and regulatory costs, have eaten into pub and club operators' margins.