Spain has imposed border controls on all air and sea travel from Italy as a row between the two EU countries intensifies.

The measures – which started at midnight (22:00 GMT) and will last for a month – come a week after Italy introduced similar restrictions following an influx of about 78,000 migrants from Morocco into the Spanish exclave of Ceuta.

Spanish officials said the documents of 5%-10% of passengers were being checked before they were allowed to disembark planes. Italy has also said its border controls are random.

The crisis has pitted Spain’s socialist leader Pedro Sanchez against Italy’s conservative leader Giorgia Meloni – who has long called for stricter EU migration rules.

Italy does not share a land border with Spain. Its government said last week that decision to temporarily suspend the ​border-free Schengen arrangement was to prevent any of the migrants who had entered Ceuta from travelling on to Italy.

Madrid dismissed this position, saying it was based on “spurious arguments” that lacked any basis in fact because the migrants who entered Ceuta had no way of entering the Schengen area.

On Friday, Spain demanded Italy reverse its checks by Sunday. Rome said they would stay until at least 15 August – when, it said, Spain “expects a new wave of migration” to hit Ceuta.

Italy has said that Spanish and EU citizens are exempt from additional checks when arriving in Italy, with these extra steps only for non-EU residents.

However, it is not clear how border officials were meant to distinguish between EU and non-EU travellers and El Pais has reported that several Italian airport terminals have seen long queues and waiting times in recent days, with passengers arriving from Spain directed to a specific line for checks.

As for Spanish controls, the authorities insists the immigration checks are random. However, a passenger arriving in Madrid on Saturday told national broadcaster RTVE that all passengers on her flight had had to show their passports.

“They told us we couldn’t get off the plane without showing our documents,” Elisa said.

Another passenger said “we were stopped and asked for identification, which the police seemed to approve of”.

Spain says its checks will stay in place until 7 September “unless a change in the circumstances that led to its adoption warrants modifying that period”.

Temporary suspensions of the Schengen agreement are not unprecedented. Italy also maintains controls on its border with Slovenia.

Italy’s decision to suspend Schengen for a month was backed by Finland and Denmark, while the Czech Republic called for Spain’s membership to be temporarily suspended.

Most of the migrants who arrived in Ceuta last week were returned within days. One hundred are believed to have died during the crossing.

Nearly 1,400 minors, some of them “very young boys and girls”, still remain there.

Spain has not announced an anticipated second wave of crossings from Morocco.

But BBC Arabic has found dozens of Facebook posts calling for a second crossing in mid-August, including some that advertised swimming equipment for sale. Six of these groups had more than 100,000 followers. Meta says it has removed posts that violate its policy.

The Spanish prime minister’s office told El Pais they were monitoring the situation but did not expect a repeat of scenes from last week.