Major banks are refusing to tell the Financial Services Authority how many of their staff are paid more than £1m.

Hector Sants, chief executive of the City regulator, told the Treasury select committee that "four of the larger banks" were not complying with his request to provide more information about how their top bankers are paid. He did not identify the banks.

Sants had asked for the information after a request from the select committee's chairman, Andrew Tyrie, who had asked for the number of bankers earning more than £1m across the six leading banks in Britain. He urged Sants to aggregate the information, rather than provide individual pay details. Tyrie also wanted to know how their pay compared with the lowest-paid board director at their firm.

Sants said that while the FSA had some "regulatory information" about pay, some of the banks had declined to provide him with the additional information that Tyrie was seeking. The FSA chief had warned last month that the banks would regard such information as "sensitive".

"In view of this, we think it right to seek the consent of all the firms concerned on their 2010 remuneration awards before we pass this aggregated information to the committee," Sants argued.

Some information has started to emerge since then. Last week Douglas Flint, chairman of HSBC, admitted the bank paid 253 staff more than £1m, while the chairman of bailed-out Royal Bank of Scotland has said the bank paid more than 100 people £1m but was not more specific.

New FSA rules have forced Barclays to admit that the average pay of 231 staff was £2.4m after the bank revealed those key employees had been paid a combined £554m. To comply with the disclosure required from the Project Merlin agreement, Barclays also conceded that five of its top managers had shared a payout of £110m.