McCabe has been brokering agreements with foreign clubs

"It will mean the Blades having first choice over their best players," said United's plc chairman Kevin McCabe.

"Either to play for us as appropriate, join our 'sister' clubs or to be placed in Europe with a opportunity to share the transfer proceeds."

The Blades already have deals with clubs in Belgium, China and Hungary and are close to an agreement in Brazil.

The Yorkshire club recently won a tender to buy into Hungarian outfit Ferencvaros.

McCabe's Hungarian firm Esplanade Kft will buy the struggling club's real estate, including their stadium in the centre of Budapest, for �8.45m.

Ferencvaros - one of Hungary's most famous clubs - are estimated to be more than �5m in debt and were relegated to the second division in 2006.

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In 2006 United became the first foreign owner in Chinese football when they bought a stake in Chengdu FC and last year the club formed a partnership with Belgium's Royal White Star Woluwe FC.

A deal with Brazilian side Sao Paulo is expected to happen in March.

McCabe has announced a provisional co-operation agreement with the Mariners - and added: "What we have agreed in principle could be of great benefit to United.

"The Mariners will benefit from loan players with some of our younger players from the academy or players from our 'sister' clubs going out to gain experience."

The formal exchange is expected to be completed in the summer and will also include the development of academies in Australia.