Tension between the U.S. government and the Egyptian military authorities has reached a new peak after it emerged that several American non-governmental workers, including the son of a member of President Obama's administration, are being prevented from leaving the country in an ongoing spat over Egypt's recent parliamentary elections.

Sam LaHood, the son of the U.S. transportation secretary Ray LaHood, was turned back at the airport in Cairo on Saturday in a significant escalation of the diplomatic stand-off between the two countries. LaHood heads the Egyptian outpost of the International Republican Institute, a conservative-leaning think tank that had been monitoring the elections held in recent weeks in the wake of the toppling of President Hosni Mubarak.

According to Politico, he was placed on a "no-fly list", without explanation, after he tried to board a plane in an attempt to escape rising hostility towards his and other foreign NGOs. LaHood had previously been named in the state-run press in Cairo.

The move follows a raid conducted on December 29 against 17 NGOs by Egyptian security forces in which computers, money and documents were seized. President Obama raised the harassment of U.S. and other foreign NGOs in a phone conversation with the Egyptian military chief Field Marshal Tantawi on January 20.

It is understood that six workers in the Cairo office of the National Democratic Institute, three of them American, have also been told they may not leave the country. NDI was among several groups involved in election monitoring.

News of the no-fly lists prompted a rash of diplomatic activity and public condemnation against the actions of the Egyptian authorities. Republican John McCain, the U.S. senator for Arizona, said that he had watched events in Egypt with "growing alarm and outrage. It's outrageous that these individuals would be held against their will by Egyptian authorities and prohibited from leaving the country."

The escalation poses a sensitive diplomatic challenge for the Obama administration. The U.S. government is coming under mounting pressure from Congress to suspend the $2 billion in aid it gives Cairo every year, largely in the form of military assistance.

While needing to be seen to protest against the Egyptian military junta's resistance to democratic change and ongoing human rights violations, the administration is also keen not to destabilize its relationship with one of its key allies in the region.

The timing of the move against the foreign workers comes as a further blow to the reform movement in Egypt that has been pushing for real democratic change in the wake of last year's popular uprising against Mubarak. The first democratically-elected parliament to sit in Egypt in 60 years convened on Monday, raising hopes that the junta would honor its promise to cede power in June.

Intellpuke: You can read this article by Guardian correspondent Ed Pilkington, reporting from New York City, New York, in context here: www.guardian.co.uk/world/2012/jan/26/american-ngo-workers-prevented-leaving-egypt