South Central Ambulance Service, which covers Berkshire, Buckinghamshire, Hampshire and Oxfordshire, said it was advertising abroad to hire 220 paramedics and technicians and 70 emergency care assistants.
The same ambulance service also confirmed it had been hiring overseas because its recruitment plans had been challenged by the nationwide shortage of paramedics.
A spokesman said: "We have been carrying out some international recruitment in Poland for paramedics where their qualifications, skills and experience are very similar to our own and meet our own high standards for staff."
The Trust said it was also looking at other countries to hire staff.
Paramedic Gavin Bashford, who works for the service, said: "We can have big delays responding to 999 calls — three, four or five hours is not uncommon — and the pressure on staff is huge."
Richard Webber from the College of Paramedics estimated that there was a nationwide shortage of between 2,500 and 3,000 paramedics.
He said although ambulance services did have many foreign workers this was the first time he had heard of official recruitment drives abroad.
He said: "One of the main problems is insufficient people being trained and recruited.
"There are not enough university programmes to meet the demand.
"It is a lack of workforce planning. A lot of trusts run their own courses, train their own people themselves.
"There is also more competition for paramedics, who are now also employed by what used to be NHS 111 (formally NHS Direct), which previously mainly took nurses."
Sarah O'Donoghue, from the union Unison, said enough staff should be trained in the UK to meet the NHS' needs.
She said: "We should not need to recruit from overseas and deprive that country of its own trained staff. We have a situation now where there are not enough trained paramedics.
"Rising demand is increasing pressure on existing staff, leading to overruns, where staff work longer than their shift, sometimes for hours, and an inability to take appropriate meal breaks.
"This causes exhaustion and impacts on work-life balance, a situation so dire that many staff are leaving the service.
"Investment in the training of ambulance staff is a priority. Recruiting abroad is a short-term fix. We need to be investing here to ensure we meet our paramedic needs."
Despite the tough conditions for paramedics here, it would likely be an improvement on working life for most of their Polish counterparts.
Paramedics in England and Wales work 37.5 hours a week, starting on a salary between £21,388 and £27,901 a year which can rise to £34,500.
In Poland they earn between £4,872 and £6,600 a year for a 37-hour week, although many work twice as many hours and some even triple hours to boost their pay.
The ambulance service in England and Wales is under severe strain and has consistently missed response time targets for the most serious cases since April.
In some regions the volume of calls is 15 per cent higher compared with last year.
Officials blame an increasing tendency of patients to dial 999 first instead of trying to arrange an appointment with a GP.
South Central Ambulance Service said agency workers were currently filling gaps while they were recruiting new staff and there was no risk to patients.
A spokesman for the Department of Health accepted that in some areas there was not enough staff to meet increased demand.
But he said: "Ambulances are making nearly 2,000 more emergency journeys every day than 2010, which is why we've employed almost 2,000 extra paramedics and provided £50million additional funding just this year to keep the service sustainable."