The refugees, stuck in a no-man's land between the two countries for the past 18 months, are demanding they be allowed to enter Jordan and then be resettled in a third country, said William Spindler, spokesman for the UN High Commissioner for Refugees (UNHCR).

"Most of them want to go to the United States," he said.

But he said the UNHCR did not have the authority to force Jordan to open its border to them.

The UNHCR is encouraging them to enter a refugee camp in Kawa, in Iraqi Kurdistan, in an area that already houses about 10,000 Iranian Kurds who are registered with the UN agency.

The UNHCR, which has offered assistance to the Kurds on Jordanian border, is "increasingly concerned," Spindler said.

"While UNHCR has done all in its power to send assistance and medical care, the refugees have consistently refused any of this help, putting the lives of the most vulnerable among them in serious danger," Spindler said.

He said three of them have gone on hunger strike in the past two weeks and their health has severely deteriorated.

The Iranian Kurds, who had fled the 1979 Islamic revolution, were until early 2005 living in a refugee camp in central Iraq, but they were forced to flee due to the insurgency there.

Jordan, already home to 1.7 million Palestinian refugees, has repeatedly refused to accept more refugees for demographic and economic reasons.