The daily Primera Hora quoted residents of the capital's central district of Santurce as saying that over the past few weeks they have been periodically visited by the primates, which are becoming a problem due to the damage they cause to crops and the risk they pose to public health.
The residents say that they had never seen any monkeys in the area, where it is no now longer strange to find the primates searching for food.
The presence of the animals in the capital has motivated the Department of Natural and Environmental Resources to track down the monkeys.
The sighting of the monkeys in the capital's central area comes after in March residents of the San Juan suburb of Guaynabo reported the presence of primates on their property.
The monkeys have been designated a menace in the southwestern part of the island and their presence led authorities in 2007 to launch a campaign to capture them during which about 2,000 were trapped.
The monkeys are not native to the island, and thus no natural predators exist for them in Puerto Rico.