A nine storey glass-fronted hotel to be built less than 150 yards from the Tower of London was granted planning permission last night.

The news came as a campaign group warned that the Tower could lose its World Heritage status because of the damage being done by developments around it,

UN heritage body UNESCO was due to send a delegate to look at the site this week to assess the impact of buildings and skyscrapers that have gone up in its backdrop in recent years.

Business and residents association, the Trinity Square Group has branded the hotel inappropriate, too bulky and said it does not fit in with the historic buildings on the square, where it will be built.

It is warning the 370-room block could contribute to the Tower being placed on UNESCO’s “in danger” list.

Resident and cllr Marianne Fredericks said: “It’s clear that UNESCO have deep concerns about the impact of inappropriate developments around the Tower.”

In a bizarre blunder, the planning application by Dutch hotel chain CitizenM was rejected by a council committee last month but the vote was not properly logged so did not count.

It was approved during a second vote by the strategic development committee on Tuesday.

Cllr Peter Golds, Tower Hamlets Tory leader, who voted against the application on both occasions, said it was “staggering” that the first vote was deemed void.

The Department for Culture, Media and Sport confirmed UNESCO would look at the site, alongside Westminster Palace, this week.

A spokeswoman said: “The issues UNESCO have highlighted relate to development in the Tower of London and Westminster Palace’s surroundings, factors which we believe are well taken account of through our existing planning regime.

“We will be arguing strongly that there is no case for putting these sites on the ‘in danger list’.”

Tower Hamlets council said it consulted fully with English Heritage and Historic Royal Palaces, which are both responsible for the preserving the Tower’s heritage, and said “neither raised objections to the proposed development”.

A spokesman said: “Historic Royal Palaces supported the proposals, highlighting the vital benefits it will bring to visitors such as step-free access to the Tower of London for the first time. They added that the development is the result of substantial dialogue between the developers, Historic Royal Palaces and English Heritage, and is an improvement to previous proposals for offices.”

UNESCO does not have to be consulted on UK planning applications, the council added.