EU officials are to investigate why Spanish police fired rubber bullets at migrants trying to swim to Ceuta.
Spain admitted that rubber bullets were fired, but said nobody was injured.
At least 14 people drowned on February 6 as hundreds of migrants attempted to reach the North African enclave from Morocco.
Together with a second Spanish enclave, Melilla, Ceuta represents the EU’s only land border with Africa.
The EU Commissioner for Home Affairs, Cecilia Malmstrom, said she was “very concerned” about Spanish police firing rubber bullets to deter migrants.
She added that the actions of any EU state protecting its borders should be “proportionate”, and should respect fundamental rights and human dignity.
“I expect clarifications from the authorities,” Ms Malmstrom said in a tweet.
On Thursday, Spain’s interior minister insisted police did not shoot directly at people, and that the bullets had not caused the deaths of any of those who drowned.