More than 1,000 patients were waiting for routine treatment at the Solent Trust in May, figures show.
The Society for Acute Medicine said the record number of people on waiting lists nationally must not be seen as the "new normal".
NHS England figures show 1,049 patients were waiting for non-urgent elective operations or treatment at Solent NHS Trust at the end of May – up from 1,020 in April, and 766 in May 2021.
Of those, one had been waiting for longer than a year.
The median waiting time from referral at an NHS Trust to treatment at the Solent Trust was seven weeks at the end of May – the same as in April.
Nationally, a record 6.6 million people were waiting to start treatment at the end of May.
Dr Tim Cooksley, president of the Society for Acute Medicine, said: “The number of patients waiting for prolonged periods for urgent care remains unacceptable and must not be seen as the new normal.
“Patients are being stuck for extortionately long periods in emergency departments and acute medical units which results in worse patient outcomes."
He said the current heatwave and a resurgence of Covid-19 cases have also increased delays, while the NHS is also battling high staff absence levels, burn out and low morale among staff.
He added: “Urgent plans are required for both short-term and long-term strategies to tackle the workforce and capacity challenges and must be a key priority for whoever the next person to occupy number 10 is.”
Separate figures show 1.6 million patients in England were waiting for a key diagnostic test in May – a rise on 1.5 million in April.
At the Solent Trust, 309 patients were waiting for Magnetic Resonance Imaging.
Of them, one had been waiting for at least six weeks.
The figures also reveal that a record 326,000 people are on cardiac waiting lists across England.
Dr Sonya Babu-Narayan, associate medical director and consultant cardiologist at the British Heart Foundation, said: “People will needlessly die or live with disability as a result of dangerous delays in getting time-sensitive heart treatment.
“NHS staff can’t do more than they are doing already, yet cardiovascular disease kills one in four in this country, and it’s certainly not going away."
A Department of Health and Social Care spokesman said: “Recognising the pressure NHS staff are under, we have provided a £150 million injection to help ambulance services, with the number of ambulance and support staff increasing by almost 40% since February 2010.
“We are making good progress on cutting longest waiting times and our community diagnostic centres are delivering over a million tests, checks and scans to help beat the Covid backlog.”