Simon Halabi, the Syrian-born billionaire, could be forced to sell one of London’s biggest property portfolios to pay off a £1.15 billion loan secured against it.

Hatfield Philips, a company appointed to restructure the loan, is understood to have demanded repayment with interest today.

The move follows a bondholder meeting on Wednesday, three weeks after a default was said to have occurred on the bonds secured against the nine London office buildings.

The trophy portfolio, which includes the offices of JP Morgan, and Aviva Tower, was found to have breached its loan-to-value covenant in June, when it was valued at £929 million, down by almost half from a value of £1.8 billion in October 2006.

Mr Halabi, who is ranked the 14th richest person in the UK and was named in a Forbes poll of the top 300 global billionaires this year, is now expected to sell off the portfolio to remedy the breach, although sources said he has some time to come to an alternative arrangement with Hatfield Philips.

Halabi family trusts also own the Naval & Military Club in St James’s Square and Mentmore Towers, a grade I listed 19th-century estate in Buckinghamshire that was once owned by the Rothschilds.

The default on the loan, which was due to expire in October, is understood to be the biggest this year on a single-issuer commercial mortgage bond.

Commercial property values have fallen by 44.1 per cent from peak to trough over the last two years, according to the Investment Property Databank. As a result of declining values and a loss of rental income from vacant office space, there was an 800 per cent increase in loans in default last year, a De Montfort University survey found.

The steep fall in values has prompted claims that the market is “at or near the bottom” from some investors. Billions of pounds of cash has been raised to take advantage of distressed sales, however so far, few ‘big ticket’ opportunities, such as the Halabi portfolio, have been put up for sale.

Agents have attributed the lack of stock to forbearance from lenders. They say that banks do not want to crystallise losses by seizing possession of assets on which loans are in default and selling them in a bombed-out market.

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