In an attempt to defuse investors' mounting criticism, World Online, the pan-European internet service provider, yesterday released details of the controversial sale by chairwoman Nina Brink of more than 6% of the company's shares ahead of the flotation.

In a statement yesterday Ms Brink said: "I would like to express my profound regret about the commotion in the market. My sale was made for entirely personal reasons to secure the financial future of my family."

Ms Brink said she would make no further statements, but the Amsterdam bourse and bourse watchdog are investigating the IPO after heavy pressure from investors.

World Online shares have lost around half their value since their March 17 listing amid controversy over sales by Ms Brink of some 15 million shares (6.35% of the firm) in late December.

Ten million were sold to Baystar, a private US investment fund in which Ms Brink is an investor.

The shares were sold at $6.04 (£3.78) apiece, World Online said.

But investors in the Dutch-based internet service provider drew little reassurance from the statement, sending the shares down €4.10 (£2.46) to €19.25.

SNS Securities analyst Bert Siebrand said: "The sheer stupidity of the whole thing is absolutely amazing. I can understand that back in August (when the sale was first agreed), we were facing a different market.

"I can understand that she wanted to cash in some shares. But she should have told us," Siebrand said

He added that even the draft prospectus, which included fewer details on the share sale, was not widely available.

"Nobody saw it. Nobody got it."

Responding to widespread allegations of a close relationship to Baystar, Ms Brink said yesterday she was a "passive investor" in the investment fund and that she had not become entitled to any profit-sharing proceeds from any World Online shares it sold.