Eighteen train services between Norwich and London have been cancelled as heat-related speed restrictions are put in place.

The region's train operator, Greater Anglia, said services will be operating at reduced speeds as temperatures continue to rise on Monday.

A spokesman said speed restrictions were necessary to prevent rails from buckling in the heat, and to protect overhead lines, which may sag when they get hot.

From midday to 7pm, eight services from London Liverpool Street to Norwich will be cancelled. Services on the hour between 12pm and 5pm will be terminated, as will the 5.50pm and 7pm.

In the other direction, from Norwich to London Liverpool Street, the following seven trains will be cancelled: 9.30am, 10.30am, 11.30am, 12.30pm, 1.30pm, 2.30pm, 3.30pm, 4.30pm, 5.30pm and 6.30pm.

Three trains from Ipswich to London - the 3.52pm, 6.49pm and 7.52pm - have also been terminated.

A Greater Anglia spokesman said: 'We are very sorry for any inconvenience caused by these heat-related speed restrictions and the amended timetable that we have to run as a result of the slower speeds.

'Advance purchase ticket holders can travel on earlier or later trains if their booked service is cancelled.'

There are more than 20 other cancellations for trains between Braintree, Southend Victoria and London Liverpool Street.

The spokesman added: 'The speed restrictions have been put in place to protect the railway infrastructure and keep services running, but at a slower speed.

'This helps to prevent rails from buckling when they get very hot, the lower speeds exert less pressure on the rail and to protect overhead lines, which may sag during very high temperatures.'

The cancellations come as the region experienced the hottest day of the year on Sunday, with temperatures rising above 30C.

Norwich-based forecaster Weatherquest predicted that the mercury will continue to rise by around one degree later today.

But it will cool off by Tuesday, as temperatures drop to a more 'comfortable' 22C, according to forecaster Phil Garner.

The village of Cavendish in Suffolk was the warmest place in the region over the weekend, with temperatures of 30.7C.