LONDON (Reuters) - Britain’s Electoral Commission is preparing to find the official campaign to leave the European Union guilty of breaking election law during the 2016 referendum, according to the former chief executive of the group.

Matthew Elliott, former chief executive of Vote Leave, said the Electoral Commission had concluded in a draft investigation that Vote Leave exceeded spending limits.

But Elliott told Sky News the Electoral Commission had committed a “huge breach of natural justice” by only listening to “the fantasists”, alleging that the watchdog had not listened to Vote Leave’s version of events.

This follows allegations by a former employee of Vote Leave that the group made a donation of 625,000 pounds ($826,250.00) to another Brexit campaign group, BeLeave, meant it violated spending rules because the groups worked together.

“Their initial conclusion is that we have overspent, that a donation we made to another group during the course of the campaign was incorrect, we shouldn’t have made that donation,” Elliott told Sky News.

The Electoral Commission said in a statement that Vote Leave had taken the “unusual step” of going public with the findings of its draft report.

“The Commission will give due consideration to the representations made,” the commission said. “We will then, at the earliest opportunity, publish a thorough and detailed closing report in order to provide a full and balanced account to the public and to parliament.”

In the June 23, 2016 referendum, 17.4 million voters, or 51.9 percent, backed leaving the EU while 16.1 million voters, or 48.1 percent, backed staying.

Britain’s exit from the bloc will mark its biggest trading and foreign policy shift in almost half a century. But Prime Minister Theresa May has struggled to unite pro- and anti-Brexit camps in her cabinet and party around a plan for future trade with the EU.