Spain has temporarily banned sailboats from a stretch of its northwestern coast after several vessels were damaged in attacks by orcas, or killer whales, in recent weeks.

The week-long ban, which came into effect on Tuesday night, applies to sailboats under 15 metres (49 feet) long and aims to protect "both people and the orcas", the transport ministry said in a statement.

It extends between the capes of the Priorino Grande and la Punta de Estaca de Bares in the northwestern region of Galicia, a stretch of about 100 kilometres (60 miles) of coast.

The first attack was reported on August 19, said the ministry. Since then there had been several more orca attacks against sailboats, causing various degrees of damage to the vessels, mostly to their rudders.

The sailboats attacked were all under 15 metres long.

A video posted on social media shows orcas swimming alongside and underneath a Spanish naval yacht in August off the coast of Galicia before the sailors realise the rudder has been damaged.

The prohibition could be extended to other stretches of the coast "following the migration routes" of the orcas, which are categorised as "vulnerable" species, the ministry added.

Orcas can weigh up to six tonnes and grow up to 32 feet in length -- about the size of a school bus -- according to the World Wildlife Fund.