Brad Pitt and Angelina Jolie's children sipped juice they call "kids' champagne" to celebrate their parents' engagement.

Brad recently popped the question to Angelina after seven years of dating. Their six children have pined for their parents to walk down the aisle for a while and were particularly excited when their dad got down on one knee.

"Brad called all the kids into a room and told them he had a surprise for their mom. He showed them the ring and explained he was going to ask her to marry him and that he needed their help," a source told British magazine Closer.

"Then they all ambushed Angie and told her to close her eyes. When she opened them, Brad was on one knee. She sort of knew it was coming, but it was very sweet. The kids had fizzy apple juice to celebrate - which they call kids' champagne - but Brad and Angelina had the real thing!"

Although Brad and Angelina aren't thought to have made many firm plans at the moment, it is suspected that George Clooney, Matt Damon, Gwen Stefani and Gavin Rossdale will be on the guest list.