MADRID (REUTERS) - Spanish authorities are looking into whether two airlines breached anti-coronavirus safety rules on three flights in recent days, the Civil Guard police force said on Tuesday (May 12).

In one case involving an Iberia flight from Madrid to the Canary Islands on Sunday, passengers themselves reported the alleged violations to the police before take-off, a guard spokesman said.

The Canary Island's Civil Guard met the plane on the runway after the flight landed and found that more than 70 per cent of the aircraft's seats were occupied, she said.

Spain's state of emergency stipulates that airlines must guarantee passengers the maximum possible separation to prevent any contagion, although it does not provide a specific occupancy ratio.

Of the three flights under investigation, police alleged that infractions ranged from non-compliance with social distancing to the absence of specific hygiene measures.

They did specify what penalties the airlines would face if the violations were confirmed.

The other two flights were another operated by IAG-owned Iberia between Madrid and Palma de Mallorca, and one between Palma de Mallorca and Ibiza operated by Air Europa, a low-cost carrier in the process of being taken over by IAG, a Civil Guard spokesman said.

Iberia said in a statement that it had "applied all initiatives needed and requested to protect customers and employees that were recommended by regulators and the industry".

An Air Europa spokesman declined to comment on the specific case but said the airline complies with all the rules and protocols.

The two flights took place on April 15 and 20, respectively, when the country was under one of Europe's strictest lockdowns.

Authorities started to phase out the lockdown on Sunday.

Under the state of emergency imposed since mid-March, most Spanish commercial aircraft were grounded as travel within Spain was limited to urgent cases.