Museum workers in Liverpool will take part in 30 days of strikes over the summer as part of an ongoing dispute over pay.
The BBC reports that walkouts by members of the Public and Commercial Services (PCS) union will affect National Museums Liverpool (NML) sites from next month.
A total of 56 days of action have already taken place in a dispute over a cost-of-living payment.
The PCS union says NML is the only government employer not to pay its staff an agreed-upon £1,500 cost-of-living payment.
However, Laura Pye, Director of NML, recently claimed that 10 out of 15 National Museums services could not fulfil the payment.
An offer by NML for a £750 one-off non-consolidated payment, an increase in annual leave to 30 days plus Bank Holidays alongside other measures, was previously rejected.
The Museum of Liverpool, the World Museum, the International Slavery Museum, the Maritime Museum, the Walker Gallery, and Sudley House are among the sites affected.
PCS General Secretary Fran Heathcote said members love their jobs but "are angry and feel undervalued".