HH Sheikh Mansour bin Zayed bin Sultan Al Nahyan

Sheikh Mansour has been forced to inject half a billion pounds in cash into Manchester City to cover his club's runaway expenditure over the past two years, Digger at The Guardian can reveal. Although that sum exceeds the gross domestic product of the Seychelles and Grenada, Mansour's spending will not stop there.

There are two main routes through which an owner can directly finance a company: either through debt in the form of shareholder loans, as Roman Abramovich did at the outset of his Chelsea ownership, or through equity. It is via the latter route – by issuing new shares to be sold to himself – that Mansour has capitalised City.

The injection of more than £399m up to December last year, much of which went on covering the £304.9m in shareholder loans that had been racked up with Mansour, was just the start. A statement released to Companies House by the board of the Eastlands club's parent, Manchester City Limited, said Sheikh Mansour had paid £46.2m in cash for new equity issued in May. "The following resolution was passed by the directors of Manchester City Limited on 5 May 2010: that 21,792,452 new ordinary shares be allotted to Abu Dhabi United Group Investment and Development Limited in consideration of the cash payment of £46.2m."

There followed another resolution in January, under the terms of which Mansour has been able to fund the club with intermittent investments of cash. On 13 July another £53m came in to the club from Mansour's coffers, taking the cash investment in the space of slightly more than three months to £99.4m and to within a whisker of £500m in total. That is just what has been specifically announced to Companies House either through City's parent company accounts or its general filings.

There are indications that Mansour's total support for the club may even exceed £650m. According to a statement of capital filed with Companies House in July, accompanying the most recent equity issue, there are now 308,465,127 ordinary shares in issue. Assuming that each one of these cost Mansour £2.12, as all those issued this year have, Mansour will have made £650m available to the club.

Contributing to the runaway expenses under Abu Dhabi's ownership have been staggering transfer fees. Between September 2008 and December 2009, City's net expenditure on transfers after player sales was about £200m; another net sum of £100m has been spent on players since then.

The wage burden also takes significant support. It is impossible to know exactly what that amounts to until the club's next set of accounts are released in February. But given that wages were the key contributor to the club's £92.6m loss in the 12 months to 31 May last year – since when almost £220m net has been splashed out on new players – it is rising fast.

"[There was] a significant increase in operating expenses – primarily driven by increased playing staff remuneration," said the club's chief executive, Garry Cook in his statement in last year's parent company accounts. "It is therefore expected that there will be further significant operating losses reported in future financial periods."

So with £300m cash spent on new players after player sales, £82.63m spent on wages in the 12 months to 31 May 2009 – a sum that continues to rise – and losses of £96.2m over the same period, Mansour will have to put his hands in his pockets again. It is lucky they are deep.