Online prediction market Intrade has shut down all trading activity immediately, saying it is investigating recently-discovered events that "may include financial irregularities."

The Dublin-based company said in a statement it has closed and settled all open contracts as of close of business on Sunday. It said it cannot pay members their settled account balances until the investigations have concluded.

Intrade allows users to place bets on future events by buying and selling shares in a system similar to the stock market. The bets could be on anything from Oscar winners to the weather.

In November, the company said it could no longer take U.S. customers after regulators charged it with illegally facilitating bets on future economic data, the price of gold and even acts of war.