"I can't because I don't know for sure," English said.
Asked if he had any recollection about whether Yang's removal from the committee was linked with his background in China, English again said he couldn't comment.
"I know about Dr Jian, and I know there has been a lot of discussion about him in the media.
"What I am saying is I can't comment on that because I can't say for sure."
Asked if he had full confidence in Yang, English said his party had no reason to believe the way Yang had conducted his role as an MP was questionable.
"Issues around that have not been raised. This is all about what happened in China...no one has raised questions in an obvious way about his behaviour in New Zealand, as a New Zealand citizen."
Asked again, English said he had full confidence in Yang as an MP.
Newly unredacted documents from Jian Yang's 2004 citizenship application show Yang, who moved to New Zealand in 1999, did not list the 15 years he spent studying and working at the People's Liberation Air Force Engineering Academy and the Luoyang Foreign Languages Institute from 1978.
Both institutions are part of China's military intelligence apparatus.
In his citizenship disclosures, Yang lists only his work and study history at the Australian National University and the University of Auckland.
In a press conference after news of his background broke, Yang said he had served as a civilian officer in the PLA and was required to not name the institutions as a condition of being allowed to leave China.
He said he was not a spy, but conceded he was involved in training spies to assess intercepted communications.
Yang said he instead referred on applications to "partnership" civilian universities which had a relationship with the military institutions.
"It is not that I am deliberately trying to cover-up. It's because the system asked me to use the partner university," he said.
This month Yang told the Herald: "I have nothing further to add to the media comments I've already made. I refute any allegations about my loyalty to New Zealand."