A militant group in Iraq said Thursday that it was holding four Jordanian workers and called on the kingdom's transport company to stop cooperation with US forces in Iraq, said reports from Dubai.

The group calling itself "Death Squad of Mujahedeen of Iraq" made the announcement in a statement quoted by the Dubai Television.

"We have taken as guests four of our brethren from Jordan in order to put pressure on their government and we don't want to turn from being hosts into other things," the group was quoted as saying in the statement.

According to the reports, the Dubai Television also aired a videotape showing the four captives, visibly nervous and sweating as they held up their passports and identity cards.

"We urge our people in Jordan to exert pressure by all means in order to put an end to the Jordanian government's support for the US occupation forces," the statement urged.

Earlier in the day, an Islamist militant group also warned to attack Muslim countries which plan to send troops to Iraq.

"We will not remain silent if troops are sent to Iraq by any Arab or Muslim country, especially by Saudi Arabia, Pakistan, Egypt and others," the group calling itself the Islamic Tawhid Group said in a statement posted on an Islamist Web site.

"We will strike with an iron fist all the traitors of Arab governments who cooperate with the Zionists," the statement said.

Iraq's hostage crisis is escalating amid chilling death threats and the killing of two Pakistani hostages by militant groups in the war-torn country.

An armed group holding the two Pakistani hostages in Iraq had announced their execution, al-Jazeera satellite news channel reported Wednesday evening.

The Qatar-based TV station said it had received a videotape showing the killings but would not air it as it was too gruesome.