Berlin, Germany (CNN) -- The two German citizens kidnapped last Sunday in a Nigerian region where many foreigners have been abducted are now free, Germany's foreign minister said Saturday.
"I'm happy that our two German countrymen are safe and sound in freedom again," Guido Westerwelle said.
"They are in a secure place in Port Harcourt. They are doing well in light of the circumstances. I thank the crisis committee and the participating German and Nigerian authorities for their tireless efforts, which made a quick and fortunate outcome of the kidnapping case possible."
The two men, ages 45 and 55, were on a trip to Azumini Beach at Imo River in southeastern Nigeria's Abia state when they were taken, security sources in Nigeria said.
One man was apparently visiting from Lagos, and the other works in Port Harcourt, the sources said, adding that the two had no security, just a local driver, with them.
The sources said it was likely an "opportunistic" kidnapping -- meaning kidnappers may have spotted the men and seen the opportunity.
Kidnappings are a big and growing problem in Nigeria, where indigenous groups have targeted oil companies in the oil-rich Niger Delta and local terrorist and criminal groups have threatened to kidnap Westerners.
The U.S. State Department's Overseas Security Advisory Council said that while most kidnapping cases involve disputes between oil companies and local groups wanting the local communities to benefit, "there has been an increase of kidnappings for ransom loosely veiled under the cloak of political activism."