Nearly a quarter of a million migrants have this year crossed the Darien Gap, the dense jungle separating Panama and Colombia, already breaking last year's record, Panama's government said on Monday.

The Darien Gap, 265 kilometres long, has become a corridor for South American migrants heading to the United States via Central America, despite its dangers.

As of Sunday, 248,901 migrants have walked through the treacherous route from Colombia, exceeding last year's record year by 600 people, Maria Isabel Saravia, Panama's deputy director of migration, told a news conference.

Along the journey are wild animals, rivers and criminal gangs who rob migrants or demand money to guide them through the jungle.

Panama Public Security Minister Juan Manuel Pino warned that the number passing through the Darien Gap could reach 400,000 by the end of the year.

Just over a fifth of the migrants recorded so far this year are children and adolescents, half of whom are five years old or younger, Saravia said.

More than 100,000 of the migrants were Venezuelans.

Also passing through the route were roughly 33,000 Haitians and 25,000 Ecuadorans. (AFP)