On a tape obtained by Associated Press Television News on Monday, the Jordanian company is warned to stop doing business with the US military or the two drivers would be killed within 72 hours.
In another incident, a group calling itself The Islamic Army in Iraq said it had "investigated" the two Pakistanis - a technician working for Kuwait's al-Tamimi group and a truck driver and decided to execute them, in a video received by Aljazeera.
The captors said the killings would be carried out based on "conclusive evidence" and Pakistani President Pervez Musharraf's announcement that Islamabad might deploy troops to Iraq.
The truck driver is an Iraqi who was delivering food supplies to US troops. He is still being interrogated, added the captors.
In a statement, the group threatened al-Tamimi's employees, saying they would share a similar destiny to that of the Pakistanis unless they withdrew from Iraq.
Part of the video broadcast showed the three men's identity cards and a photograph of them standing with Brig Gen Mark
Kimmitt, a former senior US military official in Iraq.
In related developments, another armed group holding seven foreigners extended the deadline for negotiations to spare their lives and repeated a demand that their Kuwaiti employer should pull out of the country.
The group also warned "the Indian government not to attack Muslim religious leaders"
Iraqi resistance group statement
The captives - three Indians, three Kenyans and an Egyptian, all truck drivers for a Kuwaiti firm - were seized last week by a group calling itself the Black Banners Brigade of the Islamic Secret Army.
In a video released to news companies on Monday, a masked member of the group read a statement as two armed and masked men stood at his side, behind the kneeling captives, who were dressed in white smocks.
The group said it had decided to extend the deadline in response to an appeal from Shaikh Hisham al-Dulami, the head of what Dulami calls the Detainees' Association and who on Sunday declared himself a negotiator for the hostages.
"In response to a demand from Shaikh al-Dulami, the high command... has decided to extend the deadline to complete negotiations with the consenting parties," the statement said.
"At the same time, we confirm the necessity for the withdrawal of the Kuwaiti company from Iraq for cooperating with the occupiers."
The group also warned "the Indian government not to attack Muslim religious leaders".
It was the first time the Indian government has been issued with such a warning.
It was not clear when the new deadline, which has already been extended once, would end.
An Iraqi is negotiating the
release of these captives
The Kuwaiti firm, the Kuwait and Gulf Link Transport Company, said on Sunday it had received assurances the captives would be freed.
Dozens of foreigners have been seized in Iraq in recent months, many of them truck drivers working for foreign companies delivering supplies to occupation forces or Iraqi companies.
At least six of them have been killed - four in beheadings - but most of the others have been released.
In at least two cases, the captors' demands have been met, a move that appears to have boosted the captors' confidence and may have fuelled a recent surge in abductions.