A gas pump is seen hanging from the ceiling at a petrol station in Seoul in this June 27, 2011 file photo. [Photo/Agencies]

NEW YORK - Oil prices tumbled again on Tuesday with US crude diving briefly below $30 a barrel, taking down energy shares and undercutting a rally in stocks.

Major US stock indexes rose slightly in choppy afternoon trading, after posting sharp gains initially.

Volatile Chinese markets and the deepening oil slide have shaken sentiment in equities to start 2016. China stocks closed slightly higher on Tuesday as the central bank tried to stabilize the yuan.

But oil prices slumped more than 2 percent, failing to sustain an initial rally and deepening a 1-1/2-year slide for the commodity.

US crude prices fell as low as $29.93, and were last down 2.8 percent at $30.54 a barrel. Benchmark Brent own 2.2 percent at $30.86 a barrel. US crude prices have fallen 17 percent in 2016 alone.