In November last year Sheikh Muhammad Taqi Usmani, a religious scholar not widely known outside the Middle East, sent shockwaves through the Islamic financial world with a statement that threatened to bring the fast-growing sukuk market to a standstill.

Mr Usmani, head of the religious board of the leading body that sets standards for Islamic financial products, said 85 per cent of sukuk, or sharia-compliant bonds, had broken two key principles of Islamic law.