NEW DELHI Embattled Indian Finance Minister Yashwant Sinha was facing a rough ride in Parliament Tuesday as a scandal involving the country's largest mututal fund threatened to drag in more senior officials.

Sinha, who has come under strong pressure to resign, was speak in a debate in Parliament on the scandal emerging from the United Trust of India's (UTI) decision on July 4 to freeze trading in its flagship U.S.-64 scheme.

Nearly 20 million investors were left in the lurch by the six-month freeze, which followed massive redemptions, allegedly by large unit holders who had been told of the impending freeze, AFP reported.

Former UTI chairman P.S. Subramanyam and two of his directors have already been arrested by federal investigators for suspected involvement in a 320 million rupee (3.8 million dollars) fraud case.

The ante has been raised by the Shiv Sena Party -- a right-wing Hindu member of India's governing coalition -- which has highlighted allegations that a nexus of senior civil servants and top corporations were involved in the scam.

The trail of allegations has even found its way to the door of the Prime Minister's Office.

"We want the entire truth," said Sanjay Nirupam, the Shiv Sena's main spokesman in the Upper House of Parliament.

The finance minister has so far rejected all suggestions that he should resign, insisting that the government had never interfered in the investment decisions of UTI and, therefore, could not be held responsible for its success or failure.

UTI is the largest domestic investor on the stock market and the 37-year-old U.S.-64 was considered one of the safest and most popular investment instruments.