The patrol was "forced" to open fire on a speedboat driven by a Spaniard who "refused to obey" orders in waters off the Moroccan locality of M'diq-Fnideq, the authorities said in a statement.

Four migrants were wounded, including a Moroccan woman who died of her injuries in hospital, a local official told AFP.

Those on board the powerboat were lying down and could not be seen, the official said.

The Spanish driver was unharmed and later arrested, according to the same source, adding an investigation had been opened.

Morocco -- a key route for sub-Saharan Africans trying to reach Europe via Spain -- said this month it has foiled 54,000 bids so far in 2018 by illegal migrants to cross the Mediterranean to Europe.

The figures included 7,100 Moroccans for the period until the end of August, according to figures released last week by the Moroccan government spokesman.

Since early 2018, Spain has recorded more than 38,000 arrivals by sea and land, according to the International Organization for Migration.

Since the beginning of September, social media networks in Morocco have been inundated with videos showing young people from the North African country heading to Spain aboard inflatable boats.