Cases of Zika virus infection have reportedly been detected in two New South Wales residents.

They had recently travelled in the Caribbean before heading back to Sydney, Fairfax Media reports.

“It is very unlikely that Zika virus established local transmission in NSW as the mosquitoes that spread the infection are not established here – although they are found in some parts of north Queensland,” said NSW Health’s director of communicable diseases, Dr Vicky Sheppeard.

The health department said the residents had mild cases of the virus and had since recovered.

The World Health Organisation has declared the mosquito-borne virus a global emergency following an outbreak in Brazil. It has been linked to thousands of severe birth defects.

The federal government is warning pregnant women to avoid or delay travel to countries experiencing the outbreak.