Under fire for failing to reveal the full extent of a series of irregularities at two of its nuclear reactors in northern Germany last month, Vattenfall Europe on Sunday admitted there had been further blunders at the affected plants.

Last month, a blaze broke out at the Krümmel power plant in Geesthacht, 30 kilometers (18.6 miles) southeast of northern city of Hamburg. Separately, another nuclear power plant in Schleswig-Holstein, Brunsbüttel, was temporarily shut down last Thursday about two hours before the Krümmel fire because its capacity was overloaded.

The incident triggered a fresh national debate about the safety of nuclear energy just days before an annual energy summit in Berlin focused on exploring ways to reduce greenhouse gas emissions and curb global warming.

Human error to blame?

On Sunday, Vattenfall said that human error at the plant was to blame for a further irregularity.

In the first such report from the Brunsbüttel power station near station, the company said staff at the reactor were surprised by a surge of hot water and then forgot to hold down a control button.

This caused an automatic cut-off of the reactor's water filtration system for eight minutes. There was no release of radioactivity. At the time the plant was powering up after a short circuit had closed it for three days.

The revelations that staff were unsure what to do have put the nuclear industry in Germany on the defensive. Germany's 17 reactors are to be phased out by 2021, but the industry has advocated a revival of nuclear power to reduce German carbon-dioxide emissions.

The European Union has set a goal of a 20 percent cut in greenhouse gas emissions by 2020 compared with 1990 levels, but Germany is aiming for a cut of up to 40 percent.

Energy firm's information policy under scrutiny

Energy regulators of Schleswig-Holstein state said Sunday Vattenfall had only reported the error at the last moment.

Hours later, Vattenfall Europe said it had decided to inform the public better about nuclear incidents and published on its Web site detailed technical correspondence about the accidents at its Brunsbüttel and Krümmel reactors.

Ivo Banek, a spokesman for Vattenfall, said the Brunsbüttel blunders had posed no safety risk.

However, the latest disclosures have prompted a fresh demand by Germany's opposition Greens party for Swedish-owned Vattenfall's nuclear licence to be revoked on grounds of unreliability.

"Vattenfall's scandalous approach to the legally-binding right to information shows that that this company doesn't possess the reliability that the nuclear energy law demands from operators of nuclear plants," said Reinhard Bütikofer, head of the Green Party.

On Monday, Vattenfall executives are to meet with representatives of Germany's federal environment ministry and with state authorities from Schleswig-Holstein to discuss the company's handling of the incidents and its information policies.