AsianFin -- China has imposed sanctions on former Philippine Senator Francis Tolentino, barring him from entering Chinese mainland, Hong Kong, and Macau, in a rare diplomatic move as tensions with Manila escalate.

The Chinese Foreign Ministry announced the decision on Tuesday, accusing Tolentino of engaging in “improper behavior” on matters related to China.

Tolentino, who lost his reelection bid in May, recently led Senate probes into alleged Chinese espionage activities in the Philippines and championed legislation to define the country’s maritime zones in the South China Sea—a move strongly opposed by Beijing.