The Union of Orthodox Hebrew Congregations has opposed plans to replace Greenwich Mean Time with all-year summertime, believing it will cause “tremendous hardship” for those observing religiously prescribed prayer times.

Joe Lobenstein, vice president of the Union of Orthodox Hebrew Congregations, has written to Gordon Brown objecting to proposals to shift Britain’s whole time system forward by an hour, known as Single Double Saving Time (SDST).

Campaigners for the change believe that it will boost the tourist trade and reduce traffic accidents.

But Mr Lobenstein has argued that members of the Jewish community, who wish to pray at religiously stipulated times, would not be able to say prayers before 8am in winter, which would make them late for work.

During the winter months the earliest time for morning prayer recital is at approximately 7.10am and prayers take about 45 minutes to complete.

Mr Lobenstein has calculated that if SDST were to be introduced it would mean that the earliest time for morning prayers would be at 8.10am in London.

He said: “This is causing much anxiety among religious Jews in the country and …if implemented could cause tremendous hardship for people who wish to conform to religiously prescribed prayer times.”