A boisterous shareholders' meeting on Wednesday rubber stamped the effective nationalisation of TEPCO, the operator of Japan's crippled Fukushima nuclear plant.

Around 4,000 often angry investors gave the expected formal approval to a plan to receive a 1.0 trillion yen ($12.6 billion) taxpayer bailout necessary for the company to stay afloat.

In exchange for the huge cash injection, TEPCO is to issue preferred shares to the state-run Nuclear Damage Liability Facilitation Fund, giving it a majority of voting rights, with the option to raise its stake to almost 76 percent.

In a meeting that was more about venting frustration, board members repeatedly apologised to shareholders, who have seen the value of their investments plunge by 90 percent since the tsunami-sparked meltdowns at Fukushima in March 2011 threw Japan into nuclear crisis.

The company's management of the disaster was blasted as hapless, and its apparent unwillingness to reform itself after the worst atomic accident in a generation was the object of much derision.

TEPCO's largest stakeholder -- the Tokyo metropolitan government -- joined a deafening chorus of activist shareholders in lashing out at the management.

"Japanese people and Tokyo residents no longer have the confidence in TEPCO like before," said Tokyo vice governor Naoki Inose. "It's not easy to regain that trust once it is lost."

The resignations of president Toshio Nishizawa and chairman Tsunehisa Katsumata failed to assuage the angry meeting.

Constant jeering and booing interrupted proceedings as motions were proposed that the company -- one of the world's largest utilities -- abandon nuclear power, or task an independent panel with auditing plans to hike domestic bills.

TEPCO posted a massive 781 billion yen net loss in the fiscal year to March on disaster-related costs, as well as increased imports of fossil fuels to make up for a nuclear power shortfall.

In addition to the strong operating headwinds, it is also facing massive clean-up and compensation bills from the tens of thousands of people whose homes were ruined or who lost livelihoods as a result of radioactive leaks.

Outside the meeting, dozens of anti-nuclear protesters, including those from German environmentalist group Ethecon, demonstrated ahead of the meet.

"We cannot control nuclear reactors," said a 70-year-old man who said he owned stock in the company. "We should stop using nuclear power because we cannot be sure there will be no radiation leaks once an accident hits."

But in an illustration of the competing demands of its owners, another smalltime shareholder, Yasuyoshi Katagiri, 79, said TEPCO had a duty to investors to keep operating nuclear plants.

"I bought TEPCO shares for safe investment, but the share price has gone down to one-tenth after the accident," he said.

"I think TEPCO needs to make corporate effort to recover its profitability, and I don't think it can do so without nuclear at least for now."

The fractious meeting came just weeks after Prime Minister Yoshihiko Noda gave the green light to the refiring of reactors in western Japan, ending a brief period in which resource-poor but energy-hungry Japan had been without nuclear power.

Kansai Electric Power, the operator of those reactors at the Oi plant, also faced its shareholders Wednesday, with demands the company abandon atomic generation being rejected.

The city of Osaka, a large stakeholder in the company, which supplies electricity to Japan's industrial heartland, proposed the motion, which was defeated.

Osaka's populist mayor Toru Hashimoto said KEPCO's management had "learned nothing from the (Fukushima) accident" Jiji Press reported.