As heated debate continued Monday in the Lower House over controversial security legislation, Prime Minister Shinzo Abe was forced to apologize for barking at an opposition lawmaker during a previous session and interrupting her question.

"I apologize again for my remarks," Abe said as the special Lower House committee began debating for the day the legislation that would expand the scope of the Self-Defense Forces' overseas missions.

The apology came after strong criticism from the opposition camp following Abe's heckling Thursday of Democratic Party of Japan lawmaker Kiyomi Tsujimoto.

Tsujimoto was asking about the risks to troops and civilians as a result of expanding the SDF's role.

"Come on, just ask a question!" Abe yelled, apparently irritated when her query ran into its third minute.

"(Tsujimoto) went on and on about her own opinions," Abe said on the day of the incident. "It meant she wasn't giving me time to answer, so I said that. But if my wording was a little harsh, I'd like to apologize."

The opposition camp said that apology was insufficient and demanded he formally apologize again.

The incident was not the first time Abe has taken flak for heckling.

In February, he apologized after repeatedly jeering a DPJ member about his relationship with the Japan Teachers' Union.

DPJ Secretary-General Yukio Edano warned Abe on Monday to mind his manners.

"It's the second time (that Abe has apologized for) heckling. . . . We won't tolerate another one," Edano told reporters.