(Adds arrest of South African lawyers in Namibia)
OSLO, Nov 29 (Reuters) - Shares in Norwegian bank DNB plunged more than 6% on Friday after the country's white-collar crime unit launched an investigation into its handling of payments to Namibia from Iceland's biggest fishing company.
The fishing firm, Samherji, and DNB, Norway's biggest bank, have both denied wrongdoing.
The investigation follows a report by Iceland's public broadcaster this month that said the fishing company had made illicit payments worth millions of dollars to secure fishing quotas in Namibia.
Namibia's biggest corruption scandal has led to the arrest of its former justice and fisheries ministers and cast a shadow over the country's ruling party ahead of this week's presidential and parliamentary elections.
On Friday, a Namibian magistrate ruled that former justice minister Sakeus Shanghala and former fisheries minister Bernardt Esau, who were arrested along with four others, would stay in jail over the weekend ahead of their bail application on Monday.
The six are charged with money laundering, fraud and corruptly using state office to obtain gratifications.
The two South African lawyers representing the six were also arrested on Friday for entering Namibia illegally. They pled guilty, paid a N$10,000 ($680) fine and were released.
"They testified under oath that they were not threatened or forced to plead guilty," said advocate Esi Schimming-Chase.
The lawyers, Mike Hellens and Dawie Joubert, have previously represented former South African President Jacob Zuma in various cases linked to government mismanagement.
Long regarded as only a minor risk issue for Nordic banks, economic crime has become a major concern over the past two years after money laundering scandals at Danske Bank and Swedbank.
While shares in Danske and Swedbank have plunged since 2017, falling by 65% and 47% respectively, DNB has traded near its record high in recent months and is still only 11% off its 2019 peak hit on Oct. 28.
The investigation is still in an early phase, Norwegian police said.
Separately, Sweden's central bank said on Thursday that the International Monetary Fund would examine efforts by Nordic banks and regulators to stop money laundering in Baltic countries. ($1 = 14.7080 Namibian dollars) (Reporting by Terje Solsvik; Additional reporting by Nyasha Nyaungwa in Windhoek; Editing by David Goodman and David Clarke)