China's Foreign Ministry says three Chinese construction workers kidnapped earlier this week in southern Nigeria have been released.

A brief statement Saturday said the employees of the China Civil Construction Corporation were freed Friday. It did not provide details on how they were released or whether Chinese officials paid any ransom.

Unidentified attackers abducted the workers Tuesday near the Chinese company's compound in Calabar, capital of Nigeria's Cross River state.

Criminal gangs and militants in Nigeria's oil-rich Niger Delta region have kidnapped dozens of foreign workers over the past two years, often in search of ransom payments. Most have been released unharmed.

China's presence in Africa has increased in recent years, as the nation looks for new markets and supply sources for its booming economy.

Some information for this report was provided by AFP, AP and Reuters.