Sportingbet has announced its chairman has been detained in the US while travelling on non-company business.
The British online gambling firm did not say whether Peter Dicks had been arrested, but immediately asked for its shares to be suspended "pending clarification of the situation".
In a statement, Sportingbet said: "Whilst visiting the US on non-Sportingbet business, Mr Peter Dicks, aged 64, Non-Executive Chairman of Sportingbet Plc, was detained by US Authorities at approximately 2.00am BST on Thursday, 6 September 2006. A hearing for Mr Dicks is scheduled for 2.00pm BST."
The move follows shortly after the arrest of former BetonSports CEO David Carruthers in Texas as part of a crackdown on online betting firms.
Since 2002 Sportingbet has lobbied extensively in Washington to legalise online gambling. It has placed full-page ads in the Washington Post, one featuring a picture of an Englishman with a brolley under the slogan of "Please sir, can I pay some tax?".
The firm said it will reveal further information "in due course".