Japan’s embattled Premier Naoto Kan took another blow on Tuesday as his disaster reconstruction minister quit, having caused a furor with scathing remarks to leaders of tsunami-hit regions.

Ryu Matsumoto, 60, left the post he assumed only a week earlier after he caused an outcry by giving a rough dressing-down before television cameras to a regional leader because he showed up to a meeting a few minutes late.

Matsumoto also sought to bully attending journalists into keeping the incident quiet, but instead saw his terse comments aired on TV and turn into a YouTube sensation with a hailstorm of calls for him to resign.

The latest foot-in-mouth scandal to claim the scalp of a Japanese politician piled more pressure onto Kan, Japan's fifth premier in as many years, who is already under intense pressure to resign just over a year into his post.

In a stand-off with the conservative opposition and members of his own centre-left party, Kan has promised to step down soon, but only once several key bills on disaster recovery and renewable energy are passed.

His enemies, in turn, have threatened to block key bills unless he goes.

The political bickering threatens to paralyse Japan's government as the country struggles to recover from its worst post-war disaster, the March 11 earthquake and tsunami that sparked the ongoing Fukushima nuclear crisis.

Kan, whose approval rating plunged below 20 percent in one recent media poll, in a minor cabinet reshuffle last week gave Matsumoto, then the environment minister, the new portfolio of disaster reconstruction minister.

But Matsumoto's tenure was short-lived, even by the standards of Japan's volatile politics, and on Tuesday he became the fourth minister under Kan to leave the cabinet, either in protest or because of a scandal.

Matsumoto sparked uproar at the weekend when he met the governors of two tsunami-hit prefectures, where vast areas remain devastated wastelands and tens of thousands of people are still homeless and desperate.

When the governor of worst-hit Miyagi prefecture, Yoshihiro Murai, appeared a few minutes late for a meeting, Matsumoto refused to shake his hand.

"You came in late," Matsumoto said tersely. "When a guest comes, you have to be here first before you call your guest into the room," he told the 50-year-old governor, who once served in Japan's military.

"The Self-Defense Force does that because they understand the young must honour their elders. Do you understand? Work hard," he said before rolling cameras, then telling journalists to keep his remarks off the record.

In a separate meeting with Iwate governor Takuya Tasso, Matsumoto warned bluntly that the government "will help areas that offer ideas, but will not help those without ideas. I want you to work with that kind of resolve."

When the exchanges were publicised -- with the clips drawing tens of thousands of hits on YouTube and other video-sharing websites -- offended citizens, the media and politicians voiced anger at the minister's tone.

"What is it with this condescending manner?" the liberal Asahi Shimbun asked in an editorial, questioning whether Matsumoto was fit for the job.

The conservative Sankei Shimbun asked: "Is it possible for a man who shouts such abusive language, without putting the disaster zones first, to follow the path of reconstruction together with the victims?"

In Matsumoto's farewell speech Tuesday, his eyes misty and his voice choked, he conceded that "my words were short and rough and hurt the feelings of people suffering from disaster damage. I apologise".

It was another bad day for Kan, who has been widely attacked over the slow pace of reconstruction from the quake, the construction of temporary homes for victims, and bringing the nuclear crisis under control.

"Japanese politics is going through a meltdown," said Tetsuro Kato, a political scientist at Tokyo's Waseda University.

"Prime Minister Kan is responsible for appointing a person most ill-suited for the position, which is now the most important post in Japan.

"It is the prime minister himself who should have left by now. This latest incident is a big political mistake that happened while the government is already in a terminal condition."