Mumbai, Apr 4 (IANS): The BSE Sensex tumbled over 300 points during the afternoon trade session on Wednesday as investors were cautious over escalating fears of a trade war among major global economies, as well as ahead of the outcome of the central bank's first bi-monthly monetary policy of 2018-19 (on Thursday).

While all the sectoral indices slumped, the S&P BSE auto index emerged as the sole gainer.

The barometer 30-scrip Sensitive index (Sensex) of the BSE shed over 500 points from its day's high at 33,505.53 points to trade at 32,999.82 points (around 2.50 p.m.) -- down 370.81 points or 1.11 per cent from its previous session's close.

Around the same time, the wider Nifty50 of the National Stock Exchange (NSE) declined by 119.95 points or 1.17 per cent to trade at 10,125.05 points.

According to market observers, the domestic equity markets reacted to intensifying trade war fears after China announced additional tariffs on US goods as countermeasures to the US administration's proposed tariffs covering Chinese exports worth $50 billion with a suggested tariff rate of 25 per cent.

On Tuesday, the equity indices closed with appreciable gains -- despite volatility in the global markets -- led by healthy buying in banking, auto, oil and gas, and healthcare stocks.

The Nifty50 edged higher by 33.20 points or 0.33 per cent to close at 10,245 points, while the Sensex closed at 33,370.63 points -- up 115.27 points or 0.35 per cent from its previous session's close.