* Companies says border closures are damaging business
* New case figures in Victoria rise only slightly
* New Zealand records five new cases, urges caution (Recasts, adds NZ cases, Wesfarmers and Qantas comments)
SYDNEY, Aug 20 (Reuters) - Several major Australian businesses urged a swift reopening of state borders on Thursday, even as authorities warned against complacency as new cases of the virus appear to be trending lower.
Many Australian internal borders have been closed to contain the spread of the virus, with Victoria and New South Wales accounting for almost all new cases, and most states and territories have vowed to keep them shut for months to come.
Qantas Airways Ltd QAN.AX said on Thursday the closures were severely hampering a recovery in the domestic aviation market, which, alongside a lack of international flying, would lead to a significant loss this financial year.
The airline was running only 20% of its usual domestic schedule in August due to states closing borders, which CEO Alan Joyce said "doesn't seem to make any medical sense".
Retail conglomerate Wesfarmers also called for a quick reopening of state borders, with chief executive Rob Scott saying the restrictions were causing "enormous hardship".
Prime Minister Scott Morrison, who has previously expressed frustration at the economic impact of the closures, has written to state leaders about the problem they have caused for farmers, Federal Health Minister Greg Hunt said.
The complaints came as Australia's second-most populous state of Victoria, the country's COVID-19 hot spot, reported a small increase in new daily infections to 240 cases over the past 24 hours.
The figure will buoy optimism that a hard lockdown of the state capital Melbourne is containing the spread of the virus, with new cases down from more than 700 in late July.
"There are still 240 today. So those numbers are still too high. But ... they are coming down, they're going in the right direction," Allen Cheng, Victoria's Deputy Chief Health Officer told reporters.
New South Wales recorded just five cases, although Premier Gladys Berejiklian there was still concern over the number of unknown cases.
"It's important that the community continues to embrace those COVID-safe behaviours, such as social distancing and wearing a mask," she said.
Australia has recorded just over 24,000 COVID-19 infections, with 462 deaths.
Neighbouring New Zealand, which is also battling a resurgence of cases after going COVID-19 free for more than 100 days, reported five new infections for a second day in a row, down from 13 on Tuesday.
"The next few days could be critical in breaking the back of this latest resurgence," Health Minister Chris Hipkins told reporters in Wellington.
New Zealand has now detected just over 1,600 cases of COVID-19, with 22 deaths.