New South Wales Police confirmed an 82-year-old man was stopped by Australian Border Force officers at Sydney International Airport yesterday morning.

The man's carry-on luggage was searched before the contents of his laptop and electronic storage devices were reviewed, which are alleged to have contained large amounts of child abuse material.

It comes after detectives from Eastern Suburbs Police Area Command started an investigation into the possession of child abuse material in the local area in August.

The Point Piper man was taken to Mascot Police Station and charged with six counts of possessing child abuse material.

He has been granted strict conditional bail and is due to appear at Downing Centre Local Court in February.

Mercantile Investment Company told the ASX it was aware of media speculation relating to the arrest of its director but was not in a position to comment.

In June, Brierley announced his retirement as chairman of Mercantile as it worked towards a merger with Gabriel Radzyminski's Sandon Capital Investments.

"Due to age and health issues, I can no longer give the total commitment to the company which it requires and which shareholders deserve," Brierley said at the time.

Only this week Brierley sold out of Gibb River Diamonds, nearly five years after making a failed takeover bid.

The company welcomed his exit, saying his presence on the register had hampered its ability to finance the Blina diamond project.

Mercantile launched a proportional takeover bid for Bauxite Resources (now Australian Silica Quartz Group) in 2017, but failed to reach over a 20% interest, and the same year, made an unsuccessful takeover bid for EZA Corp (now Santa Fe Minerals).

Brierley was born in New Zealand and grew his earlier investment company BIL to the country's largest company by market value.

He was knighted in 1988 for services to business.