By Alizeh Kohari

MEXICO CITY (Reuters) - Human traffickers are finding increasingly creative ways of shuttling Central American migrants through Mexico to the U.S. border and that includes hiring Uber-registered drivers.

On June 10, five vehicles carrying 34 Central American migrants were apprehended while traveling together between the northern Mexican states of Zacatecas and Coahuila, said Segismundo Doguin, a Coahuila state official at the National Migration Institute (INM).

Four of the vehicles were linked to the Uber Technologies Inc [UBER.UL] platform, Doguin said, but it was unclear whether the human smugglers had hailed the drivers using the Uber app. The drivers said they were not the owners of the cars but worked as Uber chauffeurs, he said.

Uber Mexico said in a statement that it bore no responsibility but was cooperating with authorities.

"The company does not own the cars registered on the platform, nor does it employ the drivers, who are independent contractors," Uber said.

There has been a sharp rise in the number of Central American children and families trying to reach the United States this year, a hot button issue in the U.S. presidential race. Republican candidate Donald Trump has vowed to build a wall along the U.S.-Mexican border to keep them out.

Mexican migration officials attribute the increase to migrants finding new routes past checkpoints, increasingly through varied forms of transport.

"First we saw them on trains, then on buses, then on trucks and today we see them in rented vehicles," Doguin told Reuters by telephone on Wednesday.

The drivers left the northern Mexican city of Monterrey and picked up the migrants in Matehuala, 323 kilometers (201 miles) further south, Doguin said. The caravan was headed for the city of Reynosa, 551 kilometers (342 miles) north, on the border with Texas.

The migrants told investigators they each paid 3,000 pesos ($162) to make the journey, Doguin said.

Uber said it does not offer services in Matehuala.

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Only three of the drivers were registered in the database, Uber said. One of them was dismissed nine months ago for unrelated reasons. The other two were discharged when the INM flagged the situation, the company said.

This is not the first time Uber-registered cars have been used to ferry migrants, Doguin said.

"About two months ago, seven other vehicles were detected in the area of San Luis Potosi state ... and were also in the Uber system," he said.

(Editing by Gabriel Stargardter and Simon Gardner)