It comes after talks between the country’s civil aviation workers union (Sintac) and Portugal’s directorate-general for employment and labour relations reportedly broke down last week.

Workers employed by ground handler Portway will down tools from 26-28 August despite talks between Sintac and the directorate-general over minimum service levels.

Portuguese media outlet Expresso reports Portugal’s secretaries of state for labour and infrastructure have decreed there must be provision for a minimum of one daily return flight between Lisbon and Funchal and another between Porto and Funchal.

In an earlier statement, Sintac – which postponed earlier planned strike action in April to allow for further negotiations – said it had done everything to prevent the dispute resulting in direct industrial action.

TTG has approached Portway and parent Vinci for comment. A second Portuguese media outlet, Observador, reports Sintac has sought a fresh audience with parliamentarians ahead of the strikes.

No UK airlines have publicly commented on the situation, nor has the Foreign Office. The Sintac strike notice runs from 0000 on 26 August to 2400 on 28 August.