Fifa has been urged by its own advisory board on human rights to press the government in Qatar about the impact of the kafala system on workers building stadiums for the 2022 World Cup, which campaigners have described as modern slavery.

The number of workers in Qatar, brought in from poorer countries such as India, Nepal and Bangladesh and employed to build eight new stadiums for the tournament, is expected to rise from 12,000 to 36,000 over the next year.

The report calls on Fifa to press for improved inspection of conditions and a review of required standards. Regarding kafala, the intensely criticised system of employment that ties workers to one company, the recommendation is “that Fifa actively explores ways to use its leverage to engage with the host government about the impact of the kafala system on migrant workers involved in World Cup construction”.

The report is the first from the advisory board of eight international human rights experts, set up following a report last year by the professor John Ruggie into how Fifa could meet its responsibilities under the United Nations guiding principles on business and human rights.

The report also calls on Fifa to support a thorough examination of all deaths and serious injuries sustained by workers on construction projects for next year’s World Cup in Russia, and for sanctions against companies responsible for failures. Several workers are reported to have died on World Cup construction sites in Russia and other human rights abuses have been discovered including appalling treatment of North Korean workers, whose employment Fifa has prohibited on its sites.

The vote to send the next World Cups to Russia and Qatar was made in December 2010 by the then 22 members of Fifa’s executive committee – 12 of whom have since been banned by Fifa, accused of corruption by US authorities or investigated for alleged offences elsewhere – without workers’ human rights being a central consideration.

The Qatar government announced this week a three-year cooperation with the International Labour Organisation to reform and improve conditions for migrant workers, including kafala. Many campaigners believe the global focus on Qatar which followed the award of the 2022 World Cup has prompted the government to address the abuses.

However, the report of the Fifa human rights advisory board, which says Fifa has improved its commitment to decent human rights standards, was criticised as inadequate by the Gulf expert Nicholas McGeehan. As a researcher for Human Rights Watch, McGeehan sounded the alarm recently about the dangerous climatic conditions in Qatar through the summer months and the unexplained deaths of thousands of workers, including eight in the last two years on World Cup construction sites.

McGeehan sent his research to the advisory board last month, and asked it to recommend that Fifa insist Qatar put more protections for workers in place, investigate the deaths of workers rigorously and publish its findings. However, the report only says it has requested further information about inquiries made into workers’ deaths and recommends that Fifa “support discussions” about “greater synergies” between various parts of the inspection system in Qatar.

McGeehan said he found it “shocking” that the report did not make explicit and urgent recommendations to prevent people working in dangerous conditions, and investigate the deaths of workers from heart attacks and respiratory failure. Rachel Davis, a member of the advisory board, said its report was completed in early September before McGeehan’s research was published, but that the issues were discussed last month and the board “will be taking forward our commitment to follow up on it”.