U.S. Customs and Border Protection officials say 14 packages containing nearly 16 kilograms of alleged cocaine were hidden under the shower and in the walls of the RV. (CBP)

A man and woman from Moncton are facing drug smuggling charges in Texas after being arrested at the U.S.-Mexico border with what officials say was more than $500,000 US worth of cocaine stashed in the vehicle.

Anthony William Knockwood, 41, and Heather Patricia Keirstead, 25, are charged with knowingly and intentionally possessing and conspiring to possess with the intent to distribute almost 16 kilograms of cocaine.

Knockwood and Keirstead made a brief court appearance in Brownsville on Friday, but have not yet entered any pleas, court officials confirmed. They remain in custody pending a detention hearing, likely next week, officials said.

The pair was stopped at the Veterans' International Bridge in Brownsville on Jan. 21, said U.S. Customs and Border Protection spokesman Eduardo Perez, although he declined to release their names.

The man, who was driving a beige 1997 Endeavor recreational vehicle, and his female passenger were selected for a secondary inspection, said Perez.

When officers searched the RV, they discovered 14 packages hidden under the fibreglass shower and in the walls, he said.

The packages contained 15.9 kilograms of alleged cocaine, with an estimated street value of $508,000, Perez said.

"The male and female were arrested and were turned over to U.S. Homeland Security Investigations for further investigation and of course CBP seized the narcotics and the vehicle involved," he said.

The Veterans' International Bridge crosses over the Rio Grande between Matamoros, Mexico, and Brownsville, Texas.