Swedish online gambling giant Evolution AB reached out to regulators in New Jersey and launched an internal review after a competitor accused the company of doing business in banned countries.

Chief Executive Officer Martin Carlesund said on a conference call with investors Wednesday that the company “pro-actively” contacted the regulators and initiated the internal review “to ensure that we can respond swiftly to any questions.”

Evolution held the call in response to a letter attorney Ralph Marra sent to New Jersey’s Division of Gaming Enforcement on November 12. He said the company allows its products to be played in countries where online wagering is illegal or that are subject to U.S. sanctions. Reports say the letter was based on research from private investigators hired by an unnamed US-based competitor.

Carlesund believes the people behind the letter used an internet address from a non-banned country to enter Evolution’s gaming lobby and then make it seem like the company was accepting business from markets subject to sanctions.

“We use all tools at our disposal to block play from certain countries,” he said.

A spokesperson for the private investigators disputed Carlesund’s claim, saying their research and videos show the full process of entering websites, and playing and withdrawing from Evolution games, without any use of any technical manipulation. The people were located in Iran, France, Spain, Hong Kong, Italy, and Sweden.

In the letter to regulators, attorney Marra also said a current Evolution executive told the private investigators that the company does business in countries that had U.S. sanctions against them, including Iran, Sudan, and Syria.

The methods used by the private investigators were “very questionable,” Carlesund said, adding: “I would not draw any conclusions about our culture based on that report.”