Countries and organisations planning to host events at vital UN climate talks in Glasgow next month have said they fear that increased costs at this year’s event will cause problems for developing nations.

Multiple participants said that the cost of renting Cop26 pavilions – event spaces for hosting workshops, panel discussions and keynote speeches during the conference – is considerably higher than it was at Cop25 in Madrid, with some saying it had increased by as much as 30%.

Organisations say they were told that a combination of Brexit and the pandemic were to blame for the high costs.

It comes after the Financial Times reported that one organisation was quoted nearly GBP500,000 for its space.

One official for a developing country said they were “very concerned” about operational capacity at the event, which due to the pandemic they also want to make available online, after they were told technicians could not be guaranteed unless they pay their expenses. The logistical operation, they said, is “confusing and expensive”.

They said the only transparent cost was the GBP400 a square metre rental rate, which does not include customisation and technological requirements, which they said could cost over GBP1,000 a square meter. In Madrid they said the rental cost was $400 – about GBP300 – a square meter.

An official for the World Health Organization, which is hosting a health pavilion at Cop26 with more than 60 events for global health delegates, said the “outrageous” pricing is more than double what they had originally planned for. They said organisers were blaming Brexit and a shortage of materials and human resources. They expect to spend $200,000 (GBP146,662) for a 62 sq metre space.

The official said that developing countries would undoubtedly be affected by the high costs.

“We have something aside that we can spend for these advocacy activities. But I don’t think it’s the case for many of the countries.”

They added: “We are trying to support the ministry of health of Fiji and other ministries of health from around the world, lower income countries, to come to Cop because we want the representation of the health community to be there. But even for us the prices of the flights and then the hotels are four times more than previous years.”

Another organisation said they were being forced to scale back plans for their pavilion as a result of rental costs being “30% higher than what it was in Madrid”.

The World Wildlife Fund, which is hosting a Cop26 pavilion, said pavilions play an important role in raising awareness of key issues and that there has been a “more significant increase” in cost than in previous years.

A spokesperson called on the UK government to ensure “equitable, inclusive and safe participation by developing nations and civil society”.

A UN spokesperson said developing countries that cannot afford the fees would have to speak to the UK government about it.

A Cop26 spokesperson said: “We are working closely with our delivery partners to ensure the stage is set for Cop26 when it begins later this month and are confident all pavilions will be ready in time.

“There has been unprecedented demand for pavilions at Cop26 and the impact of Covid on the supply of essential goods and materials has increased cost.”

They said the UK government has funded some of the pavilions but they have not been able to support all funding requests.