A fresh monkeypox warning has been issued in Victoria as cases rise across the state.

As of Saturday, 40 monkeypox infections have been reported in Victoria. That's up from 22 cases on August 4.

Nationally, there have been 89 cases of the virus, which is spread through skin-to-skin contact or from touching contaminated objects.

At-risk groups, including men who have sex with men, are being advised to take preventative measures as cases climb.

They should limit their sexual partners and receive the latest smallpox vaccine to protect themselves, the Victorian health department said in a statement on Saturday.

Vaccines are available in a number of sexual health clinics across Victoria although supply is limited.

Monkeypox was first recorded in Australia in May this year.

Symptoms include rashes, lesions or sores - particularly around the genitals - as well as fevers, aches and swollen lymph nodes.

The World Health Organisation last month declared monkeypox a public health emergency of international concern.

There have been more than 35,000 cases of the disease around the world and 12 related deaths, the health organisation reports.

Of Australia's 89 recorded monkeypox infections, 40 are in Victoria and 39 are in NSW, while there are also cases in Queensland (3), Western Australia (3), the ACT (2), and South Australia (2).