Moroccan authorities intercepted dozens of migrants seeking to cross into the Spanish North African exclave of Ceuta on Saturday.
More than 100 people were blocked trying to make their way to the border on the outskirts of the town of Fnideq, according to Moroccan security sources cited by Spanish media and the Reuters news agency.
It comes a fortnight after roughly 78,000 migrants arrived in the exclave by sea in a matter of hours - 100 of whom died, according to the city's mayor.
Both Spanish and Moroccan authorities had reinforced security in the area after the influx, and amid suggestions on social media that a second mass crossing attempt would take place this weekend.
The security sources said 111 people had been detained in or around Fnideq - known in Spanish as Castillejos - about 3km (1.8 miles) from the border, the majority of whom were from sub-Saharan Africa.
Moroccan police - including some in riot gear - reportedly used tear gas to disperse groups of migrants gathered on nearby hills.
Earlier this week, Rabat said it was monitoring "the circulation of social media posts and messages of unknown origin" calling for a mass crossing Saturday, warning it would prosecute organisers and participants.
Spain has deployed more than 1,500 officers to patrol the area
Security at the breakwater entrance was "10 times stronger than the previous day", Spanish newspaper El País reported.
In addition to a metal fence and a floating barrier installed earlier this week, Morocco had dispatched army officers, navy speedboats and drones to the border on Saturday.
Madrid has meanwhile deployed more than 1,500 security officers to patrol the area.
Moroccan officials seen detaining people on Saturday
The crisis has calmed since breaking out in late July, but it has sparked tensions between EU nations who share open borders as well as criticism of the Spanish government.
Italy suspended its Schengen arrangement with Spain, backed by Finland and Denmark, while the Czech Republic called for Spain's membership to be temporarily suspended - despite Sánchez noting Ceuta was not part of the Schengen area.
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