Labor has pledged to recruit 300 more nurses for South Australian hospitals if the party wins the March state election.

The promise includes 212 extra staff to support the party's commitment to open 300 extra beds across the public health system.

It also includes 12 specialist nurses for children's cancer and mental health care and 76 to target other priority needs to ensure safe staff ratios across the hospital network.

Labor has committed to enshrining nurse-patient ratios in law, in line with similar legislation in Victoria and Queensland.

Opposition Leader Peter Malinauskas said a Labor government would support the state's overworked frontline nurses who had been hard hit by overwhelmed emergency departments and the COVID-19 pandemic.

"Nurses have always been the backbone of our health public system, and this has been particularly true during the pandemic," Mr Malinauskas said on Tuesday.

"We will provide job security for our nursing workforce and observe nurse-to-patient ratios which will provide safe and quality care for patients while lifting some of the huge workload from nurses and midwives."

Premier Steven Marshall said the government had massively increased the nursing and wider health workforce as well as investing in major hospital upgrades since coming to office.

Also on Tuesday, the premier promised a returned Liberal government would establish an $18 million fund to attract more direct international flights into Adelaide while new trade offices would be established in Germany, India and Southeast Asia.

Mr Marshall said direct flights to new overseas locations would connect SA with key export and tourism markets.

The fund will target locations where there is a strategic relationship between tourism and trade - like the US, which has ties to the defence and space sectors and a population well-educated in the opportunities of an Australian holiday.

"We are recognised as a clean, green state that produces high-quality products that can't be found anywhere else," the premier said.

"Our wine, our seafood and our agriculture are viewed as outstanding on the international stage.

"We want to expand on that. We want to have more South Australian products in more overseas markets."

Among other destinations to be targeted for new direct flights are Japan, New Zealand, Vietnam and Singapore.