Rail safety chiefs have ruled out imposing a three-month deadline to end problems caused by ear-splitting horns fitted to the new generation of trains.

The Rail Safety and Standards Board (RSSB) said it could not guarantee action to silence the deafening horns in the time demanded by Hove MP Ivor Caplin.

The RSSB said it would publish new rules in August, which require a so-called 'soft tone' to be used at stations and level crossings.

And the safety body pledged a review of the ultra-loud horns, which have prompted hundreds of complaints since they were introduced six months ago.

The new horns are more than twice as loud as those fitted to old-style slam-door trains.

Mr Caplin said he was disappointed his three-month deadline had been rejected and the rail industry should not be allowed off the hook.

The RSSB said it was not sure how many trains carried horns with the 'soft tone' or how long it would take for new equipment to be fitted.

It said a night-time ban was being observed by rail operators but horns sometimes had to be sounded.

The Brighton-based Noise Abatement Society has called for the horns to be muffled or banned.

Director Peter Wakeham said the modern hooters were dangerously loud and what the RSSB was offering was unacceptable.

Aiden Nelson, the RSSB's policy and standards director, said: "The RSSB is aware of concern amongst residents over this issue and we are working to find a solution which balances the safety benefits of train warning horns and the environmental concerns of neighbours."