David Carruthers, chief executive officer of online gaming group BETonSPORTS, has been detained by US authorities while changing planes, the company said yesterday, sending the shares down more than 20 per cent.

"While changing flights in the United States en route from the UK to Costa Rica, David Carruthers, chief executive officer of BETonSPORTS Plc was detained by US federal authorities," the company said in a statement.

"The board is currently seeking clarification as to the basis of the detention," it added.

A spokesman for BETonSPORTS, which runs a large part of its operations from the Costa Rican capital, said the incident happened on Sunday night when Mr Carruthers was on his way to San Jose, but could give no further details.

Shares in the firm were 23 per cent lower at 114 pence by 0930 GMT yesterday, valuing the business at around £105 million.

The fall sparked concerns that the detention could be industry related, dragging down a raft of other internet betting companies including FTSE 100 share PartyGaming which lost as much as 11.5 per cent, Midcap 250 stock 888 Holdings and Austria's betandwin which also tumbled 11 per cent.

Last week Mr Carruthers said he thought that a US Republican-written, House of Representatives-approved Bill to crack down on internet gambling by banning banks and credit card companies from processing the payments was bound to fail due to the mountainous backlog of other US legislation.