HANOI, Jan 25 – Vietnam's VN Index rose 3.85 percent on Monday, the strongest single-day jump since March 2012, helped by a rise in oil prices earlier in the day and developments at the ongoing Communist Party congress, analysts said.

Three quarters of the shares on the benchmark index climbed, led by banks with five of the country's six listed lenders rising. Vietcombank advanced 5.56 percent and VietinBank soared 6.83 percent.

Vietnam's prime minister was among preliminary nominations for the Communist Party's central committee on Sunday, an official said, maintaining the possibility of him being in the party leadership to be decided this week.

"The fact that congress is taking place smoothly boosted the positive sentiment of the market," said Ha Le, analyst at Vietcombank Securities.

Energy stocks soared after crude oil futures extended gains on Monday on short-covering and fuel demand triggered by freezing weather in parts of the northern hemisphere. PetroVietnam Gas jumped 6.88 percent.

Shares in real-estate company Hoang Anh Gia Lai JSC also rose 6.33 percent, rebounding from Friday's record low of 7,900 dong, after the central bank rejected market rumour on investigation into HAGL.

As many as 164.3 million shares changed hands, well above their 30-day average of 122.86 million, Thomson Reuters data showed.

The market is uncertain in the coming sessions, with movements heavily depending on global oil prices and developments at the ongoing congress, analysts expected.

The congress will decide who will be Vietnam's key leaders for the next five years.

The index, Southeast Asia's best performer last year, has lost a combined 6.3 percent so far this year, compared with a 6.1 percent gain a year earlier. ($1=22,380 dong)