BEIJING, June 11 (Xinhua) -- A Chinese mainland spokesperson on Thursday slammed the flight by a U.S. military aircraft over Taiwan earlier this week, calling it an unlawful act and a serious provocation.

Media reports said a U.S. military C-40A transport aircraft flew over Taiwan Tuesday.

Zhu Fenglian, spokesperson for the Taiwan Affairs Office of the State Council, said the overflight undermined China's sovereignty, security and development interests and breached international law and basic norms guiding international relations.

"We deplore and firmly oppose the act," Zhu said.

Zhu condemned the collusion of Taiwan's Democratic Progressive Party (DPP) with external forces and expressed the mainland's resolve, will and ability to resolutely safeguard national sovereignty, security and development interests.

She warned the DPP not to misjudge the situation and urged it to immediately stop the wrong doings.