Leaders of the United States, Japan, Australia and India are expected to signal their opposition to China's attempts to change the status quo in the East and South China seas when they meet in Washington later this week, sources familiar with the matter said Wednesday.

According to the sources, a draft of a joint leaders' statement uses tougher language than in the past regarding the situation in the waters where China is stepping up its territorial claims, saying that the Quad members "oppose challenges to the maritime rules-based order," particularly in the East and South China seas.

The gathering on Friday will be the first-ever in-person Quad summit, which the U.S. administration of President Joe Biden has said will provide an opportunity to deepen ties, promote a free and open Indo-Pacific and partner on emerging technologies and cyberspace, among other issues.