The Egyptian government was stung by a wave of criticism yesterday following the appearance of a series of television adverts which appeared to warn viewers against talking to foreigners because they might be spies.

The glossy-looking commercials, which last for about 40 seconds, feature a foreign man walking into a café and then sitting down with a group of three young Egyptians.

To a doom-laden soundtrack replete with violin crescendos and plodding drumbeats, a girl at the table starts talking to the English-speaking guest about a reported conspiracy against the army.

The curious visitor nods along, before tapping a message into his mobile phone to an unknown third party. A slogan then appears on screen saying: "Every word has a price; a word can save a nation."

The adverts, which started appearing on state-owned and private television stations this week, have generated bemusement and anger among Egyptians and foreigners alike.

Taking to Twitter to vent her feelings, the Cairo-based journalist Reem Abdellatif said the adverts took Egypt back to the "Dark Ages".

Egyptian blogger Zeinobia, writing on her Egyptian Chronicles webpage, raised the possibility the campaign was an opening salvo in a war against civil-rights organisations and journalists.

She said: "I fear that this ad is an introduction for a campaign against human rights activists and journalists from abroad so they will not cover the upcoming crackdown against the Muslim Brotherhood as well [as] revolutionary powers and groups if [Ahmed] Shafik is elected as a president."

Since the Military Council took power last year, viewers who have watched the tightly controlled state-television news channels have been fed a sporadic diet of stories about "foreign hands" interfering in Egyptian politics.

The paranoia reached its apogee this year, when 16 Americans were among 43 non-governmental-organisation workers put on trial accused of illegally using foreign funds to foment unrest.

In an example of the febrile swirl of conspiracy theories doing the rounds, Al-Ahram newspaper – Egypt's most venerated publication – ran a front-page story saying: "American funding aims to spread anarchy in Egypt."

Speaking to The Independent yesterday, one Cairo-based American photographer said he felt the xenophobia in Egypt had got markedly worse in recent months. "I've felt less safe," said Cliff Cheney, 38. "I've felt more animosity."

It is still unclear who was behind the advertising campaign, but one prominent journalist who used to work for the state-owned Nile TV network told The Independent that it was probably ordered on air by the Ministry of Information.

"They used to give these kind of spots to the head of the channel," said Shahira Amin, talking about previous government-sponsored commercials. "They were prerecorded and the ministry would say it had to run a certain number of times."

Nobody from the Ministry of Information was available to comment yesterday.