Syphilis cases have reached the highest level since 1949 following a rise in unsafe sex as fears about HIV have faded, new figures suggest.

The official data shows the number of diagnoses has doubled in five years, with most cases occuring in gay and bisexual men.

It follows warnings from health officials that risky sexual behaviours - including unprotected activity, “chem sex,” the use of “hookup” apps such as Grindr - and “poz” parties where HIV positive men select sexual partners - are fuelling the rise.

The figures from Public Health England show 5,920 syphilis diagnoses in 2016 - a rise of 12 per cent in one year, and a near doubling from 3,001 cases in 2012.

PHE said that the cases were mostly associated with transmission in gay, bisexual or other men who have sex with men.