Hundreds of protesters held a rare demonstration in Kyrgyzstan on Monday sparked by a whistleblower's claims of massive official corruption.

The whistleblower who spoke to journalists was a Chinese Uighur businessman involved in the bribery that he exposed. He fled the country saying he feared for his life, but was murdered in Turkey this month.

Demonstrators held a march and a rally outside the main government building in Bishkek in response to a dramatic report claiming corrupt officials took huge pay-offs in return for turning a blind eye to smuggling millions of dollars out of the impoverished country.

The rally with many young people participating appeared to be an expression of grassroots outrage at the large-scale graft, as it was not called by any prominent politician. Local media reported up to 1,000 participants.

One protester, 57-year-old Kenzhebek, called the revelations the "final straw" for Kyrgyzstan, the second poorest of the former Soviet republics.

"Today, unfortunately, we see the authorities following the same corrupt path as previous presidents," Kenzhebek told AFP.

The report authored by the US-based Organised Crime and Corruption Reporting Project, Radio Free Europe/Radio Liberty's Kyrgyz service and the independent Kyrgyz news website Kloop.kg came out Thursday.

It cites the whistleblower as saying a powerful China-born tradesman of Uighur descent paid huge bribes to the customs service to enable the smuggling scheme.

Local media suggested up to a thousand people turned out for what appeared to be a grass-roots protest that had not been called by an prominent politician
Local media suggested up to a thousand people turned out for what appeared to be a grass-roots protest that had not been called by an prominent politician AFP / Vyacheslav OSELEDKO

The revelations have piled further pressure on the ex-Soviet country's fragile government led by President Sooronbai Jeenbekov, who has declared his aim to "struggle against corruption".

The report implicated a former customs official, Rayimbek Matraimov, nicknamed "Rayim Million" by his critics, rumoured to have bankrolled numerous political campaigns despite being a poorly paid civil servant.

Protesters in Bishkek held up placards showing Matraimov's face with the slogan: "Put Rayim in prison." Others waved football-style yellow cards.

Matraimov is officially the target of a police investigation into illegal enrichment but has not been charged and has denied any wrongdoing.

The key whistleblower behind the explosive claims, Aierken Saimaiti, a former resident of Kyrgystan was gunned down in Istanbul on November 10, before the report came out. Turkish police have detained four suspects.

He had told journalists he feared for his life and had fled Kyrgyzstan after helping underground traders funnel around $700 million out of the country, having paid kickbacks to officials.

Opposition-led protests in Kyrgyzstan brought down successive presidents in 2005 and 2010 but few reforms have followed.

The mountainous country of some 6 million people looks to China for much-needed investment but also hosts a Russian military airbase.