More than 500 Indian migrant workers have died in Qatar since January 2012, revealing for the first time the shocking scale of death toll among those building the infrastructure for the 2022 World Cup.

Official figures confirmed by the Indian embassy in Doha reveal that 237 Indians working in Qatar died in 2012 and 241 in 2013. A further 24 Indians have died in January 2014.

These come after the Guardian revealed last month that 185 Nepalese workers had died in Qatar in 2013, taking the total from that country to at least 382 over two years.

Human rights groups and politicians said the figures meant Fifa could not "look the other way", and should be leading demands for Qatar to improve conditions for the estimated 1.2 million migrant workers fuelling a huge construction boom.

The figures from the Indian embassy show that 233 Indian migrants died in 2010 and 239 in 2011, taking the total over four years to 974. Since the World Cup was awarded to Qatar in December 2010, there have been 717 recorded Indian deaths.

However, the Indian embassy did not provide further details on who those individuals were, their cause of death or where they worked. But analysis of the lists of dead Nepalese workers showed that more than two-thirds died of sudden heart failure or workplace accidents.

Qatar's ministry of labour and social affairs told the Guardian: "With specific regard to these new figures, we were aware that local media had previously reported some of these headline numbers, and we are clarifying them. Clearly any one death in Qatar or anywhere else is one death too many – for the workers, for their families, but also for Qataris who welcome guest workers to our country to perform valuable jobs. We are working to understand the causes of these deaths – as these statistics could include a range of circumstances including natural causes, and road safety incidents, as well as a smaller number of workplace incidents."

Nicholas McGeehan, a Gulf researcher for Human Rights Watch, said: "These figures for Indian deaths are a horrendous confirmation that it isn't just Nepalese workers who are dying in Qatar."

Jim Murphy, the shadow international development secretary, said: "Preparations for the 2022 World Cup cannot go on like this – the trickle of worrying reports from the construction sites of Qatar has become a torrent.

"Some of the practices we know are taking place in Qatar amount to forced labour, and there are widespread concerns that the death toll could reach well into the thousands if nothing is done."

Last week, a hearing at the European parliament heard from human rights groups, Fifa and other interested parties after a resolution was passed last year calling for action on the issue as construction of 2022 World Cup venues begins in earnest.

Despite the Qatar 2022 organising committee implementing a new charter relating to construction on its stadiums and the ministry of labour highlighting an expanded inspection programme, human rights groups and trade unions have repeated their call for structural change in the face of hundreds of deaths.

In November, Amnesty warned in a damning report that workers were enduring 12-hour days in sweltering conditions and living in squalid, overcrowded accommodation.

The International Trade Union Confederation (ITUC) has warned that up to 4,000 workers may die before a ball is kicked in 2022 without meaningful reform of the kafala system, which ties workers to their employers, and stringent control of the myriad construction companies and subcontractors involved.

The ITUC, which has campaigned consistently for better rights for migrant workers across the Gulf, has called the publication of the charter a sham because it does not deal with structural problems created by the kafala system..

Many workers arrive in Qatar already heavily in debt, having paid huge sums to middle men to secure contracts in the fast growing Gulf state.

A senior executive at one of Qatar's largest banks told a conference in Bahrain last month that the Gulf state would spend £123bn on infrastructure projects in the next four years alone. The hosting of the World Cup is an integral part of Qatar's unprecedented 2030 National Vision building project.

There are an estimated 1.2 million migrant workers in Qatar. Those from India make up 22% of the total, with a similar proportion from Pakistan. Around 16% are from Nepal, 13% from Iran, 11% from the Philippines, 8% from Egypt and 8% from Sri Lanka.

The Qatar World Cup organisers believe that by holding their own contractors to higher standards they can create momentum for change and that improved rights for workers could be one legacy benefit of hosting the tournament.

The ministry of foreign affairs has also emphasised that it is stepping up efforts to hold contractors to existing labour laws, sanctioning 2,000 companies in 2013 and a further 500 in January 2014 alone.

The statement from the Qatari ministry of labour and social affairs added: "Where any liability is found to rest with employers, the ministry …and Qatari law authorities will pursue these cases through the relevant legal channels. We have increased the number of trained labour inspectors by 25%, and continue to hire new inspectors, with over 11,500 random spot-checks of workplaces carried out in the past three months.

This, in order to enforce our existing labour laws, with the aim of the prevention of any further workplace incidents."

Law firm DLA Piper has been engaged to prepare a report on all issues surrounding Qatar's use of migrant labour, which is expected to be published next month.

But human rights groups have maintained that Qatar must prove it is serious about reforming its labour laws. Amnesty's James Lynch, who wrote last year's report, called on the Qatari and Indian authorities to provide more detail on the circumstances of the deaths.

"This issue is not restricted to one country of origin," said Lynch. "It is critical that the Qatari government works urgently with the governments of migrant workers' countries of origin to investigate the main causes of migrant workers' deaths and develops a transparent plan to address these, particularly where deaths relate to industrial accidents, work conditions and access to healthcare."

Fifa has asked Qatar to provide evidence of meaningful progress in reforming labour law but the president of world football's governing body, Sepp Blatter, has said its status as hosts is not under threat.

Murphy, who will travel to Nepal and Qatar in the coming weeks, said: "Fifa cannot simply look the other way. Football's governing body should be leading demands for change, not dragging its feet."