Scientists say hormone replacement therapy could hold the key to creating a male contraceptive pill.

Researchers looked at compounds used in HRT and the female contraceptive pill and their effects on men.

The results of the trial have been presented to the British Endocrine Societies meeting in Brighton.

Researchers found HRT compounds tibolone and nomegestrol acetate (NOMA) appeared to have a contraceptive effect in men.

However, the team from the University of Manchester and Leeds General Infirmary warned it could be more than ten years before it was available for use.

A number of trials are under way into alternatives to the contraception options open to men.

The latest studies, led by Professor Fred Wu, found tibolone and NOMA suppressed pituitary gonadotrophins - the hormones which stimulate sperm production.

Researchers said NOMA showed particular promise because it had no adverse metabolic effects.

Other male contraceptive formulations in production have been shown to decrease levels of HDL cholesterol, which protects against heart disease.

NOMA did not have this side-effect in the men who took part in the trial.

Professor Wu said: "These are very early studies but the HRT preparations show promise as male contraceptives.

"NOMA would have a particular advantage to those pills currently in development, as it doesn't seem to decrease HDL cholesterol levels."

Many women have expressed concern about men's ability to take responsibility for contraception.

Professor Wu said future therapies for men would be simple.

He said: "The formulations would be almost as easy to use as the female Pill, just one a day and a testosterone injection once a quarter."

The Family Planning Association said any research in the area of male contraception was welcome.

A spokeswoman said: "We know from calls to our helpline that men are keen to share the responsibility for contraception.

"We get a lot of men asking where they can get the male Pill and showing they want to share the burden with their wife or long-term partner."