Belgian police were investigating a letter threatening attacks against El Al airlines that was found at the Brussels international airport over the weekend, a police spokeswoman said Monday. "I can confirm we found a letter in a toilet room of the Zaventem airport on Sunday," said federal police spokeswoman Evie Claes. She did not give more details on the letter. The El Al office in Belgium said it had been informed of the letter but had no comment to make. "It's a letter we've heard was found in the toilets, but we don't know anything else about it," said an official at the El Al office in Brussels, speaking on condition of anonymity. She said the airline was well-guarded and was continuing operations as usual.