Neither side would confirm, however, the findings of an investigation or if any appeal was under way.
"We have a disciplinary process at Liffe and if there are cases we are investigating, we do not comment," said a Liffe spokeswoman. "And that is the case with any kind of investigation, be it criminal, or in this case a breach of Liffe rules."
It is not known which rules, if any, GNI is alleged to have broken. The company declined to comment.
Penalties can be stiff: Liffe can impose a maximum fine of pounds 250,000 for each of its trading rules broken by a company.
Three weeks ago The Independent on Sunday broke the story that Refco Overseas, one of the world's largest independent futures brokers, is the focus of a three-year investigation into market rigging by regulators at Liffe. That investigation is due to conclude in the next few weeks.
According to four sources at Liffe, Refco traders systematically participated in what is known in the trade as "front-running''. This practice, banned by the exchange, involves a trader taking a large order from a client but buying options on his own account before he executes it. Since an order often pushes the market up, the trader can then sell at a profit.
If GNI is found to have broken any rules, it could be a source of embarrassment to Liffe's chairman Brian Williamson. Until he joined Liffe last year, he was non-executive chairman of Gerrard Group, the parent company of GNI which he founded.
In 1994, GNI was fined pounds 21,600 by the International Petroleum Exchange over breaches of rules and trading procedures by its floor trading staff. The breaches included executing trades by means other than open outcry; failing to register or properly execute a number of cross trades; and abusing a client order by trading away from the market price.
Liffe is expected to switch to electronic trading in the next couple of months, which will end its open outcry system with its traders clad in war-scarred cotton jackets.