BEIJING, June 30 -- Chinese shares bounced back from early morning losses and closed sharply higher on Tuesday following a nightmarish fortnight.

The benchmark Shanghai Composite Index surged 5.53 percent to finish at 4,277.22 points. It fell more than 5 percent in the early morning to 3,847,88 points, extending losses from a peak of 5,178.19 points on June 12.

The Shenzhen Component Index gained 5.69 percent to close at 14,337.97 points.

Tuesday's rally came at a time when rattled investors began to debate whether the year-long bull run had ended as a decline of 20 percent from the recent peak is usually considered the advent of a bear market.

The market has taken a turn for the worse since June 15 on fears over the sustainability of soaring share prices pushed up by a frenzy of speculation, as well as government moves to cool margin trading, a high-risk practice in which investors borrow money to invest in stocks.

The market's losing trend became unstoppable when the Shanghai Index tanked 7.4 percent on Friday, triggering concerns about systemic financial woes.

On Monday, the Shanghai index slipped further by falling 3.34 percent despite forceful easing as the central bank announced on Saturday that it would simultaneously cut China's interest rates and reserve requirement ratio, a move widely considered a gesture to forestall market declines.