The GMB union will meet ambulance representatives on Monday to discuss up to six more strike dates, Sky News understands.
It comes after talks with Health Secretary Stephen Barclay failed to reach an agreement earlier this week.
Yesterday, about 25,000 ambulance workers across England and Wales went on strike in a dispute with the government over pay.
Staggered walkouts by paramedics, call handlers, drivers and technicians from the Unison and GMB unions took place over a 24-hour period.
NHS England warned that some people would have to make their own way to hospital.
While members of the armed forces and private providers were once again drafted in to help cover services, as was the case during the first strike day on 21 December.
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More strikes are scheduled, with nurses due to walk out next Wednesday and Thursday, and another ambulance strike the week after, on 23 January.
Despite no deal being reached following the talks with Mr Barclay on Monday, the health secretary did agree to look into a suggestion to backdate next year’s NHS pay deal to this January.
But it is understood representatives of the GMB union are set to meet again next week to discuss whether industrial action should escalate.
It comes as new NHS figures show Ambulances in England took an average of one hour, 32 minutes and 54 seconds in December to respond to emergency calls such as burns, epilepsy and strokes.
This is the longest on record and well above the target of 18 minutes.
Response times for urgent calls, such as late stages of labor, non-severe burns and diabetes, averaged four hours, 19 minutes and 10 seconds – again, the longest on record.
The figures for England also showed a record 54,532 people waited more than 12 hours in A&E departments last month from a decision to admit to actually being admitted.
And the proportion of patients seen within four hours in England’s A&Es fell to a record low of 65% in December.
Responding to the latest NHS England performance data, RCN Director for England, Patricia Marquis, said: “Today’s figures suggest this picture is only going to get worse. Hospitals are full, many patients face very long waits to be admitted from A&E and the waiting list for routine treatment remains sky high.
“The government has had months and months to address this but has not acted. They must row back on years of underinvestment in nursing, starting with an immediate pay rise.
“Nursing is saying enough is enough and standing up for their patients. Next week’s strikes are in protest at unsafe care.”
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Who is striking and when?
Mr Barclay held further talks this morning with medical unions which were described as “constructive” by the chair of council at the British Medical Association (BMA).
Speaking after the meeting, Professor Philip Banfield told reporters: “The tone was not confrontational, the tone was collaborative.
“The secretary of state was a consummate politician in listening mode. It’s what happens next that’s the important thing.”
Professor Banfield said doctors feel they have been “driven” to the point of considering strike action because “no-one is listening to us”.
“We’ve got about six weeks, haven’t we, to sit down and try and resolve the situation. None of our doctors want to strike, they would prefer that this was resolved before we got into that situation,” he said.