Rumors had swirled about the reasons for the probe before Saturday's announcement in China, where President Xi Jinping has launched a sweeping drive stated as aiming to root out graft.

Rubio said that the firing of the general was "part of a pattern we've seen over the last few years, which is a purge in their military."

"They're spending a lot of money on their military and obviously some of these guys are stealing that money and they're trying to address that," Rubio told the Senate Foreign Relations Committee.

"It's an issue internally in their system. They're obviously not sharing with us or talking to us in depth about any of that, but it's certainly something we watch with interest," Rubio said.

China announced Saturday that Zhang Youxia, the senior vice chairman of its powerful Central Military Commission, and another senior official were being put under investigation for "serious violations of discipline."

Xi, often described as the most powerful Chinese leader in decades, has championed crackdowns on corruption since taking office more than a decade ago.