Jan 9 (Reuters) - Indian shares were flat on Friday as investors paused after a four-session slide, staying cautious ahead of a U.S. Supreme Court ruling on tariffs due later in the day.

The Nifty 50 added 0.01% to 25,877, while the Sensex slipped 0.01% to 84,173.50 as of 9:56 a.m. IST. 

Nine of the 16 major sectors declined. Small-caps and mid-caps traded flat.

Nifty and Sensex have lost 1.7% and 1.8%, respectively, over the past four sessions after U.S. President Donald Trump hinted that tariffs on Indian goods could be raised over New Delhi's purchases of Russian crude. Investors are awaiting a U.S. Supreme Court ruling on the legality of Trump's tariffs. If deemed "illegal", the U.S. government could be forced to refund nearly $150 billion to importers.

"Markets are under pressure after Trump approved a bipartisan bill imposing sanctions on Russia, which also gives the U.S. authority to penalise countries that buy large quantities of Russian oil and gas, including tariffs up to 500%," said Vishnu Kant Upadhyay, assistant vice president of research and advisory at Master Capital Services.

Bucking the trend, BHEL rose 2% after securing an order worth 54 billion rupees from JV Bharat Coal Gasification & Chemicals.

BHEL lost 10.5% in the previous session, after Reuters reported that India's finance ministry has planned to scrap five-year-old curbs on Chinese firms bidding on government contracts.

Eternal gained 2.2% after Goldman Sachs reiterated its "buy" rating, saying  it disagreed with the extent of bearishness being priced into the online food-delivery firm's stock.

Eternal has dropped about 17% in the last three months, lagging the benchmark indexes' 3% rise.

Vodafone Idea gained 3.3% after unveiling a dues repayment timeline, capping annual payments at $13.79 million for the next six years, easing near-term cash flow pressure.

(Reporting by Bharath Rajeswaran and Vivek Kumar M in Bengaluru; Editing by Sumana Nandy and Nivedita Bhattacharjee)

By Bharath Rajeswaran and Vivek Kumar M