Paramedics covering Wigan will be taking part in strikes every weekend until October.
Another 26-hour stoppage is scheduled by North West Ambulance Service (NWAS) from 6am on Saturday to 8am on Sunday, as part of an ongoing pay dispute.
Ambulance bosses have expressed their disappointment at the series of walkouts after what they describe as “positive” talks with the GMB union.
The weekend stoppages follow four previous bouts of industrial action and union leaders say they will continue until there is a “genuine commitment to find a resolution” to the pay stalemate.
Mike Bouey, regional GMB organiser, said the stand-off centres around job re-evaluation proposals dating back more than 13 years.
He added: “This is the last situation our paramedics wanted to find themselves in, but they are desperate for management to listen to their side of the story.
“They’ve been waiting a long time for their job to be re-evaluated for the years between 2005 to 2016.”
The union claims NWAS acting chief executive Michael Forrest is choosing to ignore the issue.
Lisa Ward, interim organisational director for NWAS, confirmed the NHS trust had been notified of the union’s intentions.
“I am in no doubt their actions will effect patients although we will be doing all we can to minimise any impact on the public,” she said.
“It is fair to say the action so far has had little impact on our ability to respond to patients. However this extended period of action is highly likely to cause some delays, particularly to less urgent calls.
“We have robust plans to ensure as much cover as possible but we urge the public to help us by only calling 999 for life-threatening or potentially life-threatening emergencies.”