Corruption-fighting agencies in South Asian countries lack the power and independence to properly investigate politicians and officials for fraud entrenched in the region, a watchdog said.
A report released by Berlin-based Transparency International on Thursday said that many agencies needed their government's consent to investigate suspected corruption cases, while others faced massive political interference during their investigations.
"The region is characterised by a vicious cycle in which a highly elitist and unaccountable political culture remains largely unchallenged because the very actors who can bring those in power to task are being systematically silenced," said Srirak Plipat, Transparency International Asia-Pacific director.
The report comes days after India's Congress party, embroiled in a string of corruption scandals during its 10 years in power, was defeated in national elections.
The study, released in Nepal's capital, Kathmandu, examines efforts to fight corruption in six South Asian countries - Bangladesh, India, the Maldives, Nepal, Pakistan and Sri Lanka.
"As long as nobody brings the corrupt to justice, South Asia's leaders run the risk that future growth only benefits the powerful, doing nothing to help the half-billion South Asians who still live in poverty," said Plipat.
In many cases, South Asian watchdogs are deliberately weakened by their governments, while officials also use agencies to settle scores with political opponents or to protect powerful backers, Transparency International said.
In Nepal, the head of the national anti-corruption watchdog has faced allegations of fraud himself for several years and is currently the subject of several investigations.
With the exception of Sri Lanka, the countries surveyed have legislation to protect the public's right to information - but citizens are often unable to use the laws effectively because of official reluctance to respond to requests, the report said.
The study also found that whistle-blowers confront huge dangers when they attempt to expose corruption, with most South Asian countries lacking laws to protect them. Officials who try to expose wrongdoing face the risk of being transferred or removed from office.
South Asia is considered one of the world's most corruption-ridden regions, according to the watchdog, with high-profile politicians embroiled in huge corruption cases and many citizens complaining of being forced to pay bribes for essential services.