Two Chinese nationals kidnapped by gunmen near Nigeria's capital, Abuja, last weekend have been released, police said Tuesday.

The men, who are aged 45 and 50 and work for a construction company, were held for "24 hours of captivity" after they were ambushed, police spokesman Umar Nurman told AFP.

They have undergone tests in a hospital in Abuja and appear to be in good health, he added.

Their release followed "extensive pressure from the search party", Nurman said. It was unknown whether a ransom had been paid.

The exact timings of the kidnapping and release also remain unclear, though police previously said the men were ambushed on their way to Abuja on Saturday afternoon.

Kidnappings targeting prominent Nigerians and foreigners, especially in the oil-producing south, were rife in the 2000s until a 2009 government amnesty reduced unrest in the region.