(Releads on trade minister calling summit on corruption)
By Terje Solsvik and Stine Jacobsen
OSLO, April 4 (Reuters) - Norway's government invited the heads of top company boards to talks on corruption as offshore banking revelations added to a string of allegations over the ethics of some of the country's largest firms.
The invitation follows the leak of more than 11.5 million documents from the files of a Panama-based law firm, allegedly showing how clients avoided tax or laundered money.
Among the leaked material on hundreds of thousands of clients in multiple jurisdictions were revelations that top Norwegian bank DNB helped customers set up offshore companies in the Seychelles.
DNB, in which the state owns 34 percent, said it regretted assisting about 40 customers in setting up the firms between 2006 and 2010, and that the practice had ended.
"It's the customers' responsibility to report their own funds to tax authorities. Still, we believe we should not have contributed to establishing these companies," Chief Executive Rune Bjerke said.
"The structures could be abused for tax evasion."
Trade and Industry Minister Monica Maeland said in a statement on Monday she had invited board leaders of 30 firms to the talks in June.
"There has recently been revealed several cases of corruption and ethical issues in the broader sense. As owner we have clear expectations to how the companies work with corporate responsibility," she said.
"I want a status (report) on how the companies work to prevent corruption and have therefore invited the chairmen of the companies under my ministry to a meeting."
In July four former top executives at Yara, one of the world's biggest nitrate fertiliser makers, were sentenced to prison terms for paying bribes in Libya and India. They are appealing.
A parliament committee is looking into cases concerning oil firm Statoil, telecoms company Telenor and aluminium producer Norsk Hydro about their own or their affiliates' dealings in Angola, Uzbekistan and Tajikistan respectively.
All three firms, in which the state has stakes, have denied wrongdoing.
Norsk Hydro said it expected it would attend the June meeting.
"Speaking generally, we have a good dialogue with our biggest owner (the state) and have had regular meetings with the ministry about these issues," said a Norsk Hydro spokesman.
In a separate statement, the minister said bank DNB must now provide a written explanation of its policy of helping clients set up offshore companies.
"DNB says this should not have happened and that the bank should not have participated. That I agree to," Maeland said.
Statoil was not invited to the June meeting as it is supervised by the oil ministry, the trade ministry said.
Yara said it was not able to comment on Monday. DNB and Telenor were not immediately available for comment. (Additional reporting by Ole Petter Skonnord; Editing by Andrew Roche)