"US citizens traveling to Aqaba on Friday are advised to use the Dead Sea Road," the embassy said in a memorandum on its website.

"US citizens are reminded that even demonstrations intended to be peaceful can turn confrontational and possibly escalate into violence," it added.

In addition to a rally at the Grand Husseini Mosque in central Amman, the US diplomatic mission expected demonstrations to be held at three southern cities-Maan, Karak and Aqaba, all of them are located on the Desert Highway.

The Islamic-led opposition and the pro-democracy March 24 group said they planned rallies on Friday amid reports that the government intended to go back on a decision to send more than 80 rights activists to the State Security Court on charges of holding "illegal demonstrations and resisting policemen".

One protester was killed and more than 120 wounded on March 25 when policemen used force to disperse hundreds of March 24 activists, drawing sharp reactions from local rights organizations and the Human Rights Watch.

King Abdallah on Thursday visited Maan, a traditional hotbed for Islamic fundamentals about 200 kilometers south of Amman, and promised steps to improve the inhabitants' standard of living, including the building of a military hospital, clinics and schools.

He also revealed that he was mulling a general amnesty for prisoners and detainees from the city and other localities.

The monarch has instructed the government of Prime Minister Marouf Bakhit to carry out "speedy and real" political reforms, but Islamists and other opposition parties accused the Cabinet of bowing to pressure groups seeking to shelve the purported reforms.