July 22 (Bloomberg) -- India's benchmark stock index rose to its highest in almost a month on speculation the ruling coalition will survive a showdown in parliament, speeding up legislation that would bolster overseas investment in the country.

Reliance Industries Ltd., the nation's most valuable company, advanced to its highest since June 26. ICICI Bank Ltd. and HDFC Bank Ltd., the country's two biggest private lenders, climbed to their highest in a month.

``The market is speculating that the government will scrape through the trust motion,'' said Mahesh Patil, who helps oversee $9.6 billion in assets at Birla Sun Life Asset Management in Mumbai.

The Bombay Stock Exchange's Sensitive Index, or Sensex, rose 311.28, or 2.3 percent, to 14,161.32 as of 11:48 a.m. local time. The S&P CNX Nifty Index on the National Stock Exchange advanced 89.15, or 2.1 percent, to 4,248.65.

Reliance gained 1.5 percent to 2,185 rupees. ICICI added 4.1 percent to 669.50 rupees, the highest since June 26. HDFC Bank gained 5.8 percent to 1,146 rupees, its highest since June 18. State Bank of India rose 2 percent to 1,379 rupees.

Prime Minister Manmohan Singh must win the backing of a majority of the lower house to remain in office after his communist allies withdrew support on July 9 over a U.S. accord that will allow India to import nuclear reactors and fuel.

A victory is needed for Singh to complete the accord he struck with U.S. President George W. Bush in 2005. The government said the agreement will give India access to nuclear energy without having to submit military related programs for inspection and without having to sign the Non-Proliferation Treaty, which the country considers discriminatory.

Overseas funds bought a net 5.36 billion rupees ($132.8 million) of Indian stocks on July 17, reducing their net outflow this year from equities to $6.87 billion, according to the nation's stock market regulator.

The following were among the most active stocks traded on the Bombay and National Stock Exchanges. Stock symbols are in parentheses after company names:

Areva T&D India Ltd. (ATD IN) gained 96.5 rupees, or 6.4 percent, to 1,614.90. The local unit of the world's biggest maker of nuclear reactors said its board will meet on July 29 to consider splitting its stock.

Bharat Heavy Electricals Ltd. (BHEL IN) rose 80.7 rupees, or 5.4 percent, to 1,587. India's biggest power-equipment maker said first-quarter profit rose 33 percent, better than analysts' estimates. Net income gained to 3.84 billion rupees in the three months ended June 30. That beat the 3.3 billion rupees median profit estimate in a Bloomberg survey. Sales rose 34 percent to 43.3 billion rupees.

Maruti Suzuki India Ltd. (MSIL IN) dropped 54.15 rupees, or 8.4 percent, to 593, the most since Oct. 30. The maker of half the cars sold in India reported first-quarter profit declined 6.6 percent to 4.66 billion rupees.

Tech Mahindra Ltd. (TECHM IN) climbed 38.9 rupees, or 5.7 percent, to 719.70. The Indian software services provider in which BT Group Plc is the second-largest shareholder said it won a $700 million order from BT group, a U.K. telecommunications company.

United Spirits Ltd. (UNSP IN) jumped 165.15 rupees, or 16 percent, to 1,215. The maker of the McDowell brand of Indian whisky climbed the most in more than three-and-a-half years after first-quarter profit rose 34 percent to 1.17 billion rupees. Sales gained 32 percent to 10.2 billion rupees.

Zee Entertainment Enterprises Ltd. (Z IN) added 6.05 rupees, or 3.1 percent, to 199.70. India's biggest publicly traded media company said its board will meet on July 30 to consider buying back its shares.

To contact the reporter on this story: Pooja Thakur in Mumbai at pthakur@bloomberg.net

Last Updated: July 22, 2008 04:06 EDT