Men who have fertility treatment have a higher risk of prostate cancer in later life, a study has suggested.

The research - in the British Medical Journal - looked at 1.2 million pregnancies in Sweden over 20 years.

Men who had ICSI - a treatment specifically for male infertility - had an increased prostate cancer risk.

But Prostate Cancer UK said researchers must look at a much broader age range before concluding men who have fertility treatment are at higher risk.

Researchers from Lund University in Sweden used data from national birth and cancer registers.

They looked at more than a million births between 1994 and 2014, and at cancer cases.

Most babies - 97% - were conceived naturally, and 20,618 (1.7%) were conceived using IVF, although the data does not show if fertility issues lay with the man or the woman.

Some 14,882 (1.3%) births resulted from ICSI, where a single, good-quality sperm is selected and injected directly into an egg.

ICSI was first used in Sweden in 1992, with every case recorded by the register.