Two more companies are suspending their US operations ahead of the introduction of new laws restricting gambling over the internet.
Processing payments from online poker will soon be illegal in the US
Fairground Gaming said US clients would be unable to play online casino and poker games once President Bush signs a Congressional bill into law.
Fireone Group, which processes online credit card payments for the gaming industry, is to stop US transactions.
Both firms said they would cut costs as part of a wider restructuring.
The online gaming sector has been left reeling by US lawmakers' decision to make it illegal for banks and credit card firms to process gaming payments.
Many gaming firms derive the bulk of their income from the US, and he news has led to their stock market values plummeting.
The bill needs Presidential approval before it becomes law but this is expected in the near future.
Shares in World Gaming were suspended on Monday due to uncertainty about the company's future, while there has been speculation that Empire Gaming will seek to diversify away from the gaming market.
Fireone Group said it would stop processing gaming-related transactions originating from the US once the bill becomes law, adding that this would have a negative effect on its business.
Fairground Gaming said that it had enough cash to continue trading despite the fact that 70% of its sales come from the US.
But it added that it was reviewing its overall strategy.
"The board is attending urgently to appropriate cost-cutting measures," it said.