The march of London's skyscrapers looks set to continue unchecked after the UN watchdog charged with protecting sites of international importance delayed a move to place parliament – which is being obscured by a rash of new towers – on its endangered heritage list.

Unesco was due to put Westminster on its List of World Heritage in Danger when it met recently in Doha, Qatar. According to the draft agenda prepared before the meeting, the watchdog was concerned that plans for a series of skyscrapers south of the Thames threatened to spoil the views of the Palace of Westminster, Westminster Abbey and nearby St Margaret's church.

However, following intense lobbying from the UK ambassador to Unesco, the measure, which would have raised embarrassing questions about the government's regard for the country's most prestigious cultural assets, as well as London's skyscraper policy, was dropped. Instead Unesco said it would give the government until next February to respond to its concerns.

Richard Tamplin, a member of the Twentieth Century Society, the organisation that championed the South Bank Centre, said he was dismayed by Unesco's decision to drop Westminster from the list. "Pressure from a world heritage body can make a lot of difference to the protection of the historic heritage in this country," said Tamplin, speaking in a personal capacity. "Conversely, when such a body gives in to pressure and does not undertake its responsibilities seriously, then not only does it fail the heritage but it also loses its own credibility and authority."

Campaigners had hoped Unesco's intervention would draw attention to an array of high-rise developments mushrooming across the capital. Unesco had been particularly concerned by plans to demolish Elizabeth House, a 1960s block on the South Bank, and replace it with a 29-storey tower. But many other developments are now in the pipeline.

Last week Lambeth council approved another controversial 200-metre-high skyscraper in Vauxhall on the site of a Victorian warehouse. The go-ahead of the Vauxhall Bondway has prompted concerns that views of parliament from south of the Thames will be obliterated.

In its submission to the council, English Heritage, the government-funded body that protects the country's most important cultural sites, warned that the skyscraper would be part of a "wall of development" that would "visually challenge the dominance of the Palace of Westminster". English Heritage said part of the reason Unesco had given the site a Universal Outstanding Status was that it recognised "the banks of the Thames as a symbol of British democracy and power". English Heritage said: "This value is seriously challenged by the scale of development."

A spokeswoman for Unesco declined to say why it had declined to put Westminster on its endangered list as it had previously intended. "The UK must submit an updated report responding to the committee's concerns by next February, and the site will be discussed again at next year's committee meeting in Bonn, Germany," the spokeswoman said.

A Lambeth council spokeswoman said it was reviewing the situation regarding Elizabeth House and a decision would be taken on its redevelopment, probably before the end of the year.

The pace and scale of development south of the Thames has alarmed local residents. A scheme to partly demolish the Shell Centre on the South Bank and turn it into a predominantly luxury housing development has become another potential flashpoint.

George Turner, a Lambeth resident who is mounting a legal challenge against the development, said residents were being ignored in favour of developers. "The whole planning system is there to try to ensure that new buildings meet the needs of our society and respect our past," Turner said. "But the government, the mayor of London and Lambeth council seem to think that developers should be allowed to build anything, anywhere, at any time. Large developments are waved through regardless of the facts, regardless of the rules and regardless of the views of Londoners who will live with the new-built environment for generations to come."

Henry Owen John, a conservation director with English Heritage, said Unesco's decision to resist putting Westminster on its danger list was "pretty standard", but was not the end of the saga. "Although it has not been added to the endangered list, there is a significant risk of this happening," he said. "With any major modern city like London it's inevitable that some new developments will potentially affect its World Heritage Site status."