Tunisia has ordered its brokerages to suspend securities trading by 123 firms, sources said, including Dubai's Shuaa Capital and the parent companies of at least two publicly listed Tunisian firms.

The firms were named in a confidential list issued at the end of February by Tunisia's financial authorities. They are trying to pry loose the grip of overthrown President Zine Al-Abidine Ben Ali's extended family on the North African country's economy.

"We were told not to let these companies invest or withdraw money from their trading accounts. Their accounts are frozen," a Tunis-based broker told Reuters.

The list, mostly privately held Tunisian companies, was issued by Tunisia's financial markets regulator, Conseil de Marche Financier.

Dubai-listed investment bank Shuaa Capital, a notable foreign inclusion in the list, declined to comment on whether it was aware of the existence of the Tunisian list.

"Shuaa Capital has no past or current dealings with the former president of Tunisia," a Shuaa Capital spokeswoman told Reuters.

The list, which was seen by Reuters, also includes BINA Corporation, majority shareholder of Carthage Cement as well as Princesse Holding which holds stakes in Ennakl Auto and Bank Ziytouna.

Also named was Tunisian holding company Investec, which is controlled by Ben Ali's son-in-law Marwan Ben Mabrouk, who holds a stake in mobile operator Orange Tunisie.

"We received a list of 123 companies...to freeze the accounts of companies linked to people close to Ben Ali," said another broker in Tunis.

BINA Corporation, Princesse Holding and Carthage Cement could not be reached for comment, while Ennakl declined to comment.

On Thursday, Tunisia's interim government seized the 51 per cent stake in Orange Tunisie owned by Ben Mabrouk through Investec.

When contacted, Tunisia's central bank and financial markets regulator both declined to comment.

Earlier this month, the interim government said it would freeze assets of 112 people close to the ousted president pending the completion of investigations into corruption.

Tunisia's attempt to bring businessmen who prospered through ties with the previous regime is mirrored in Egypt, which is expected to expand a list of people whose assets have been frozen pending investigations into links with former leader Hosni Mubarak.