Glenn Maud, one of Britain’s most secretive property tycoons, is working on an urgent £2.5bn refinancing plan after one of his funds, Propinvest, breached banking covenants.

Maud, whose portfolio includes a 50% stake in Citigroup’s landmark Canary Wharf tower, is in talks with a consortium of banks and hopes to refinance Propinvest, his investment vehicle, within weeks. The negotiations will be a key test of banks’ appetite to support highly leveraged property investors and will be closely watched by many in the property industry. If completed it will be the first major property refinancing deal since the credit crisis began over a year ago.

Maud has been one of the most active private investors in recent years, building a portfolio reported to be worth around £5bn. As well as the Citigroup tower, Propinvest also owns a number of major UK shopping centres.

Recently, Barclays Capital declared that more than £300m of commercial mortgage-backed securities linked to Propinvest were in breach of a “loan-to-value covenant” ruling that a “special servicing event” had occurred. “[Barclays Capital] are in talks with the borrowers regarding the breaches of the credit agreement,” said the bank in a statement.

Maud is one of a number of property investors who has breached the covenants on commercial mortgage-backed securities (CMBS) - a popular form of financing in the final years of the property boom.

At the end of last week ratings agency Fitch changed its outlook for the commercial mortgage-backed securities sector from “stable” to “negative”. Fitch said the outlook for the junior bonds secured against these schemes was now “negative”.