The halachic battle over the North-West London eruv intensified this week, after opponents claimed the support of the world’s most influential authority on Jewish law.

A letter from Jerusalem-based Rabbi Yosef Shalom Elyashiv was cited in a statement publicised in strictly Orthodox circles to further warn people against using the eruv.

But the London Beth Din stood by its new Shabbat boundary — which allows observant Jews to push prams, wheelchairs and carry some otherwise-prohibited items. “We continue to have every confidence in the integrity of the eruv,” a spokesman said, “and it is due to enjoy its third week in operation tonight.”

The new statement against the eruv came from Gateshead community head, Rabbi Bezalel Rakow, one of several leading strictly Orthodox rabbis who have publicly rejected its use. “I hereby warn all who fear and dread the name of God to listen to the words of the learned rabbis of England who signed the appeal not to use the North-West London eruv,” he said this week.

In it, he includes a letter from Rabbi Elyashiv, containing an argument about measurements used in the construction of the eruv, one of the most complex halachic issues.

Rabbi Elyashiv — who last year also condemned the first edition of Chief Rabbi Sacks’s book, “The Dignity of Difference” for containing unorthodox views — is especially significant, being an authority to whom London Beth Din head Dayan Chanoch Ehrentreu often turns for advice.

But the London Beth Din was adamant that the intervention made by the Israeli sage made no difference to the validity of the eruv. “For the North-West London eruv, we have adopted the measurements prescribed by three of the greatest authorities of the last century,” the spokesman said.

One leading member of a strictly Orthodox congregation said, meanwhile, that “a lot of people are very unhappy” with the communal dispute. “We cannot allow this campaign against the eruv to continue.”

In a separate development, eruv officials have settled a dispute with Barnet council over a complaint that pruning regulations were ignored by US contractors during its installation.

Barnet officials have welcomed suggested changes in the configuration of eruv poles on Wildwood Road, near Hampstead Heath, to avoid any further damage to trees. The proposal involves removing three eruv poles, using a lamppost to support the eruv wire. The idea has won support from the heath superintendent and from the Conservation and Amenities Committee of the Hampstead Garden Suburb Residents Association.

Eruv Committee chairman Edward Black said: “I am hopeful Barnet Council will accept our proposal and that the problem of possible damage to trees on Hampstead Heath will be solved.”

He also denied reports that eruv wires had been deliberately damaged last week and that officials had been forced to arrange urgent repairs.