The Jersey Financial Services Commission (JFSC) is scrutinising the international starchitect's purchase of 49.6 per cent of employees' shares in the business, just weeks ahead of the planned sale of part of his practice to an as yet unknown strategic investor.
Employees have been offered an equivalent of a proportion of their annual salary in return for the shares in a deal that could potentially be worth hundreds of millions of pounds to Foster.
A spokesman from ESOP told the AJ: 'We can confirm the JFSC is taking a look at the events leading up to the sale of the employees' shares, but we are pleased that it happened in Jersey because it is a very good regulatory body.
'At the moment we have a limited amount of knowledge of the details of the shares - it's all a little opaque,' he said.
'It could be that everything has been done to the book but it's just not been communicated very well. The JFSC will ask some questions, but it is impossible to say how long it will take.'