Mumbai, Feb 22 (IANS): Heightened tensions between Russia and Ukraine, as well as persistent selling by FIIs plunged India's key indices -- S&P BSE Sensex and NSE Nifty50 -- during the late afternoon session on Tuesday.

Besides, high crude oil prices along with subdued global indices added weight to the downtrend.

On Monday, Russian President Vladimir Putin ordered the deployment of troops into two separatist areas within Ukraine, after recognising their independence, a move that some fear puts Kiev and Moscow one step closer to a military conflict.

This act led to to a slide in global stocks' value while it catapulted prices of commodities, including crude oil and gold.

On the domestic front, the two key domestic indices had a gap down opening and kept falling for the fifth session.

All sectoral indices traded in the red led by Realty, Metals and Telecom.

At 1.45 p.m., Sensex traded at 56,785.36 points, down 1.56 per cent or 898.23 points from the previous close.

Nifty traded at 16,927.35 points, down 1.62 per cent or 279.30 points from the previous close.

"Nifty opened gap down on Feb 22 and kept falling for the fifth session as escalating tensions over Ukraine and fresh regulatory scrutiny on China's tech sector drained investors' nerves," said Deepak Jasani, Head of Retail Research, HDFC Securities.

"Nifty could take support from recent lows of 16,809-16,836."

According to Gaurav Garg, Head of Research CapitalVia Global Research: "All Asian markets were trading lower on the global front, as escalating geopolitical tensions between Russia and Ukraine spurred a sell-off in global stocks."