Oil prices jumped on Monday as Western allies imposed more sanctions on Russia and blocked some Russian banks from a global payments system, which could cause severe disruption to its oil exports.
Brent crude LCOc1 rose $4.82, or 4.9%, to $102.75 by 1028 GMT after touching a high of $105.07 a barrel in early trade.
The Brent contract for April delivery expires on Monday. The most active contract, for May delivery, was up $4.74 at $98.86.
U.S. West Texas Intermediate (WTI) crude CLc1 was up $4.62, or 5%, at $96.21 after hitting $99.10 in early trade.
"Growing concerns about disruptions to Russian energy supplies are pushing oil and gas prices up sharply," said Commerzbank analyst Carsten Fritsch.
Russia is facing severe disruption to its exports of all commodities from oil to grains after Western nations imposed stiff sanctions on Moscow and cut off some Russian banks from the SWIFT international payment system.
Russian crude oil grades, which account for about 10% of global oil supply, were hammered in physical markets.
Goldman Sachs bank raised its one-month Brent price forecast to $115 a barrel from $95 previously.
"We expect the price of consumed commodities that Russia is a key producer of to rally from here - this includes oil," the bank said.
President Vladimir Putin put Russia's nuclear deterrent on high alert on Sunday.
Russian forces seized two small cities in southeastern Ukraine, the Interfax news agency said, but ran into stiff resistance elsewhere.
Talks between Ukraine and Russia have started at the Belarusian border, a Ukrainian presidential adviser said, aiming to agree an immediate ceasefire.
"If there's any progress made in this meeting, we're going to see a sharp reversal in markets - we'll see stocks rise, the dollar rise and oil fall," said OANDA analyst Jeffrey Halley.
British oil major BP BP.L decided to exit its Russian oil and gas investments, opening a new front in the West's campaign to isolate Russia's economy. BP is Russia's biggest foreign investor.
"The sanctions and the exodus of Western oil companies are likely in the medium to long term to result in lower Russian oil and gas production," said Fritsch.
The Organization of the Petroleum Exporting Countries (OPEC) and allies led by Russia, a group known as OPEC+, are due to meet on March 2. The group is expected to stick to plans to add 400,000 barrels per day (bpd) of supply in April.
Ahead of the meeting, OPEC+ revised down its forecast for the oil market surplus for 2022 by about 200,000 bpd to 1.1 million bpd, underscoring market tightness.
(Reporting by Bozorgmehr Sharafedin in London/Additional reporting by Sonali Paul in Melbourne and Alex Lawler in LondonEditing by David Goodman)