The UK's main financial regulator has been visiting asset management firms to review their compliance with existing rules on the unbundling of dealing commissions – ahead of tougher impending European rules on the practice.

The Financial Conduct Authority has visited a range of investment firms across the UK in recent weeks as part of a market-based review of the way they use client money to pay brokers for services such as execution, research and corporate access, according to people familiar with the matter.