By Stephanie Kelly

NEW YORK (Reuters) -Oil prices slipped Friday after sharp rises earlier in the session on concern over potential global supply disruptions from sanctions on major crude exporter Russia.

The April Brent crude futures contract was down $2.17, or 2.2%, to $96.91 a barrel at 11:41 EST (1621 GMT), after climbing as high as $101.99. The more active May contract shed $1.79 cents, or 1.9%, to $93.63.

U.S. West Texas Intermediate (WTI) crude fell $1.58, or 1.7%, to $91.23 a barrel, after hitting a session high of $95.64.

For the week, Brent was set to rise about 3.5%, while WTI was on track to fall around 0.2%.

On Thursday, Russia’s invasion of Ukraine boosted prices above $100 a barrel for the first time since 2014, with Brent touching $105, before paring gains by the close of trade.

The assault was the biggest attack on a European state since World War Two, prompting tens of thousands of people to flee their homes. On Friday, Russian missiles pounded Kyiv, families cowered in shelters and authorities told residents to prepare Molotov cocktails to defend Ukraine’s capital from an assault that the mayor said had already begun with saboteurs in the city.

On Thursday, U.S. President Joe Biden responded to the invasion with a wave of sanctions that impede Russia’s ability to do business in major currencies along with sanctions against banks and state-owned enterprises.

Britain, Japan, Canada, Australia and the European Union also unveiled sanctions, including a move by Germany to halt certification of an $11 billion Russian gas pipeline.

However, Russia will not have its oil and gas flows specifically targeted by sanctions, a U.S. official said. The country is the world’s second-largest crude producer and a major natural gas provider to Europe.

Biden also said the United States is working with other countries on a combined release of additional oil from their strategic crude reserves.

“Obviously the talk of the SPR (Strategic Petroleum Reserve) is still out there and that’s been a negative factor, but uncertainty going into the weekend is going to be supportive,” said Phil Flynn, senior analyst at Price Futures Group in Chicago.

Top buyers of Russian oil, however, are struggling to secure guarantees at Western banks or find ships, sources told Reuters.

A deal among OPEC+ oil producers is showing no cracks so far, OPEC+ sources told Reuters, and the group is likely to stick to a planned output rise of 400,000 barrels a day in April despite crude topping $100 a barrel.

The alliance, which groups the Organization of the Petroleum Exporting Countries and producers including Russia, meets on Wednesday to make the decision.

(Additional reporting by Emily Chow in Beijing; editing by Jason Neely, Kirsten Donovan and David Gregorio)