The Dubai-based oil and gas services firm, which has struggled as a result of a downturn in the hydrocarbons market, has asked banks to consider extending the maturity of its debt and restructuring repayments, the sources said.

Although the company, which operates a fleet of offshore supply vessels that service the oil and gas industry, has not missed any repayments, one of the sources said it had breached certain covenants, without elaborating.

Stanford Marine did not immediately respond to a Reuters request for comment.

A fund managed by Abraaj, whose investment portfolio spans emerging markets, owns 51 percent of Stanford Marine, with the remaining stake held by Abu Dhabi-based investment firm Waha Capital.

Stanford Marine's restructuring talks are not linked to Abraaj's recent dispute with four investors in its $1 billion healthcare fund, but one of the sources said some bankers had questions over whether an escalation of Abraaj's problems could have an impact on the restructuring process.

Another person familiar with the process, however, said Stanford Marine's restructuring discussions were completely independent from Abraaj and Abraaj's talks with investors in its healthcare fund were entirely independent from Stanford Marine's situation.

Abraaj is considering selling part of its investment management business and has hired Deloitte to examine its business, including the healthcare fund, as it tries to limit the fallout from a row with some of its investors, including the Bill & Melinda Gates Foundation and the International Finance Corp (IFC), over the use of their money in the fund.

The $325 million loan that Stanford Marine is restructuring was signed in June 2015 and was provided by a group of banks including Noor Bank, Barwa Bank, Ajman Bank, United Arab Bank, Qatar Islamic Bank, and First Gulf Bank - now part of First Abu Dhabi Bank.

Stanford Marine in 2013 hired banks to help arrange a stock market listing in London, Reuters reported at the time, citing sources, but Bloomberg reported in 2014 that plans were delayed as Abraaj sought potential buyers.

(Editing by Louise Heavens)

By Tom Arnold and Davide Barbuscia