A prominent human rights group has accused Jordan's intelligence agency of making arbitrary arrests and abusing political dissidents.
HRW's Christoph Wilcke says some suspects were tortured
In a new report, Human Rights Watch said some suspects had been held for long periods without being charged and are denied access to lawyers.
It called on Washington to raise the issue with Jordan's King Abdullah II during his visit to the US this week.
The Jordanian authorities have denied the allegations.
Jordan's main intelligence service, the General Intelligence Department (GID), has carried out "waves" of arrests of political dissidents, most of them Islamists, since 2000, according to the report.
HRW's Christoph Wilcke added that many suspects were held in solitary confinement when first arrested and there were "serious allegations of ill-treatment and sometimes torture".
The allegations are based on the cases of 16 people arrested by the GID.
Of the 16 people investigated in the report, 13 have been released without trial, two are still being held without formal charge and one has been acquitted.