Shahidan Kassim, a minister in charge of national security, said the government has dispatched the Malaysian Maritime Enforcement Agency and the navy to the area to monitor the situation.
Shahidan was quoted by the national Bernama news agency today as saying that legal enforcement action would be taken if the Chinese vessels are found to have entered Malaysia's exclusive economic zone.
Shahidan and other ministry officials could not be immediately reached for comment.
China claims almost the entire South China Sea. Brunei, Malaysia, the Philippines, Taiwan and Vietnam also have overlapping claims. Tensions have ramped up since China began a massive land reclamation program in the strategically vital sea lane in 2013.