Anglo-South African financial services group Investec is looking to acquire the international arm of wealth manager Coutts, whose clients include the Queen of England, Sky News reported.

The news website report said that there are at least half a dozen parties that have expressed interest to buy Coutts International, which is being sold by its owner, Royal Bank of Scotland (RBS).

Investec have reportedly hired advisers to help it plot a takeover. The firm has been expanding its wealth management activities rapidly in recent years, and has experience significant increase in profits.

The company is expected to face stiff competition for the Coutts International unit. Its prominent rivals include Singaporean bank DBS and French lender Societe Generale, which are in talks to team up to buy the unit. Other bidders include Intesa Sanpaolo, the Italian bank, Brazil's BTG Pactual, and Julius Baer, the Swiss private bank.

While it is unclear exactly how much the Coutts International business is worth, analysts estimate that the unit could fetch between £500m ($766m, €638m) and £650m.

Government-backed RBS earlier announced its plans to sell the international arm of its private bank, Coutts, after the bank identified the unit as non-core.

The move will split Coutts into two businesses, one based in Britain and the other in Zurich, Switzerland, from where it operates in Hong Kong, Singapore, Monaco, Dubai and Abu Dhabi managing assets worth about $36bn.

RBS had noted that since Coutts' international clients are richer than those in the UK, splitting the businesses will make sense as services required by both client groups are different.

In 2013, Coutts International's operating profit was 103m Swiss francs (€84.8m, £67.7) excluding provisions.