AMMAN: Angry relatives of a Jordanian who died in detention last week blocked a road to neighbouring Syria on Sunday, accusing authorities of killing him after he allegedly helped Syrians buy arms.

"We blocked the international road from (the border town) Ramtha to Syria to protest against an autopsy report and to demand a trial for the killers," Fathi Zubi, brother of Najem, 20-year-old taxi driver, who died in prison on Wednesday night, told AFP.

"We will continue our protests until the the killers are identified," said Zubi, whose family belongs to one of the largest tribes in northern Jordan.

Zubi said his uncle, who is a physician, "attended the autopsy and said the cause of death was asphyxiation."

"According to my uncle, by brother was strangled. He did not hang himself as the report claimed," he added.

Residents in Ramtha, a town north of Amman, confirmed to AFP that the road has been blocked by large rocks and burning tyres.

Police spokesman Mohammad Khatib played down the incident, saying, "around 30 people blocked road."

"The situation is currently being addressed by MPs, senators and others who are in talks with Zubi's family," Khatib said.

On Thursday, protesters in Ramtha torched the governor's offices, the courthouse and a police car before a riot squad broke up the demonstration using tear gas.

A Jordanian official, on condition of anonymity, said that day: "Najem took two Syrians, who had arrived in Jordan a few days earlier, to an arms dealer.

His mother insisted on Sunday "my son Najem had a clean record."

"He was supposed to get a new job in the Civil Defence Department later this week. I do not understand why he was arrested," she told AFP.

Meanwhile, the Jordan Football Association decided to hold a national league match in Amman instead of Ramtha, "for security reasons."

Several residents of Ramtha, which lies across the border from the restive Syrian city of Daraa, often smuggle clothes, food and other goods across the frontier.

But border controls have been stepped up since the outbreak of a deadly anti-regime revolt in Syria in March.