|India's supreme court has reprimanded Singh for failing to investigate a minister over the telecoms scandal [AFP]
The Indian prime minister has defended himself against accusations of inaction in a $40bn telecoms scandal, while vowing that anyone found guilty in the case will be punished.
Manmohan Singh is accused of failing to act on allegations that his telecoms minister acted improperly. The ruling Congress party's popularity partly rests on his "Mr Clean" image.
"There should be no doubt in anyone's mind that if any wrong thing has been done by anybody, he or she or will be brought to book," Singh said on Saturday in his first public declaration on the controversy.
The scandal centres around Andimuthu Raja, who was forced to resignas the federal telecoms minister on Sunday amid allegations that his ministry sold second-generation, or 2G, mobile phone licences at reduced rates to undeserving applicants.
Proceedings in India's parliament were adjourned on Friday after opposition members stalled the proceedings demanding to know why Singh's government took a year to investigate the 2G licensing scheme.
The opposition has been blocking parliamentary business all week, calling for an all-party investigation into the issue.
India's supreme court issued a sharp and rare rebuke to Singh on Thursday, saying the government's delayed response was an "extremely serious matter".
The state auditor issued a damning report on Tuesday saying the 2008 sales went against the government's wishes for a transparent bidding process and resulted in significant revenue losses.
The opposition claims Singh failed to act against the telecoms minister because he feared upsetting his coalition partner. Raja is a member of the DMK, a regional party from Tamil Nadu, whose backing provides the Congress party a majority in parliament.
The auditor's report said the sale "lacked transparency and was undertaken in an arbitrary, unfair and inequitable manner" and that many of the 122 licences were given to "ineligible applicants" who "used fraudulent means" and then quickly sold their stakes at a high premium.
India's telecom regulator on Thursday recommended that 62 licences given to five companies be cancelled.
Transparency International this year ranked India 87 out of 178 on its Corruption Perceptions Index - a slide downward from its position a year earlier as the 84th most corrupt country out of 180.
Suresh Kalmadi, the chief organiser of October's Delhi Commonwealth Games, which was heavily criticised over corruption, was forced to step down from a senior position in the Congress party earlier this month.
The supreme court has asked Singh's office to explain why it took a year to address parliamentary demands that Raja be investigated.
The Central Bureau of Investigation, India's corruption watchdog, has been investigating the 2G pricing since October 2009.
GE Vahanvati, India's attorney general, must file an affidavit on behalf of Singh by Saturday, according to a court request. Vahanvati will then defend the prime minister in person at the supreme court on Tuesday.
He is expected to say that Singh, who has not commented on the court criticism and is not expected to attend, followed correct procedures.
The court is expected to inquire why Singh remained silent on a plea by an opposition member of parliament to prosecute Raja.
The judges cannot punish Singh because no case has been filed against him, but any criticism is likely to be a blow to his credibility.
Singh has widely been considered one of India's cleanest politicians since taking charge as prime minister in 2004.