A sudden influx of migrants swimming into the Spanish enclave of Ceuta in northern Africa is a serious crisis for Europe, Prime Minister Pedro Sanchez said on Tuesday, vowing to re-establish order promptly amid heightened diplomatic tensions with Morocco.

Spain deployed troops to Ceuta to patrol the border with Morocco after about 8,000 migrants, many from Sub-Saharan Africa and including 1,500 minors, entered the enclave on Monday and Tuesday by swimming in or climbing over the fence.

Armored vehicles were guarding Ceuta's beach on Tuesday, and soldiers and police used batons to clear migrants from the beach and threw smoke bombs to discourage others from crossing.

Footage of the beach at about 8 p.m. showed nearly all migrants had been cleared.

Spain said about 4,000 migrants had already been sent back to Morocco under a readmission deal.

The regional leader of Ceuta criticized what he described as Morocco's passivity in the face of Monday's surge. Morocco on Tuesday recalled its ambassador to Spain for consultations, official news agency MAP reported.

The agency disclosed no further details on the reasons behind the Moroccan government's decision to recall Karima Benyaich. Earlier on Tuesday, Benyaich was summoned to the Spanish Ministry of Foreign Affairs in Madrid when thousands of Moroccans entered Ceuta.

"This sudden arrival of irregular migrants is a serious crisis for Spain and Europe," Sanchez said in a televised address before his arrival in Ceuta.

Ceuta, with a population of 80,000, is on the northern tip of Morocco across from Gibraltar. Along with another Spanish enclave, Melilla, it has long been a magnet for African migrants seeking a better life in Europe.

(With input from Reuters, Xinhua)