Ecuadoran authorities said Friday that a Colombian bus that crashed near Quito, leaving 23 people dead, was carrying at least a half a ton of marijuana hidden in its floor.
Nearly 600 plastic-wrapped packages of the drug were found by a sniffer dog in the wreckage of the bus, which crashed on Tuesday, national anti-narcotics police director General Carlos Alulema said.
He told reporters that three buses from Colombia had already been stopped this year and "more than 400 kilos of cocaine and 600 of marijuana were found in similar circumstances."
The South American countries share a border regularly used by drug-trafficking gangs to ship cocaine to the United States.
Colombian prosecutors said Thursday that 80 kilos of cocaine had been recovered from the bus.
But Ecuadoran prosecutor Ruth Palacios told the press conference "marijuana was found, solely and exclusively."
Colombia said Wednesday that 19 of the 23 victims were its citizens.
Palacios said the authorities would question the 22 injured passengers, mostly Colombians, to try to determine "who is responsible" for the drug-trafficking.
"Then it will be determined who stays and who is allowed to leave," she said.
The bus overturned and crashed into three houses after a collision with an all-terrain vehicle near Quito.
Ecuador transport colonel Julio Barba said the driver "probably overused the brakes... which produced an overheating of the brake system leading to a loss of control of the vehicle."
One of the two drivers, who was injured in the crash, has been arrested.
Traffic accidents are among the leading causes of death in Ecuador, averaging seven deaths and 80 injuries a day.