New York's main contract, West Texas Intermediate for delivery in September, was up four cents at $107.50 a barrel in mid-morning trade.
Brent North Sea crude for October delivery gained four cents to $110.44.
"Oil prices remain supported by the situation in Egypt with fears that it could spread across the Middle East," Desmond Chua, market analyst at CMC Markets in Singapore, told AFP.
"There is still some concern about supplies passing through the Suez Canal and Sumed Pipeline," he said.
Thirty-six Islamist prisoners were killed Sunday during an attempted jailbreak in Egypt, police said, bringing to almost 800 the death toll over five days as authorities continued a crackdown on supporters of ousted president Mohamed Morsi.
The bloodshed in Egypt has drawn widespread international condemnation, with senior European Union diplomats set to hold emergency talks on Monday to discuss the situation and future EU action.
Although Egypt is not a major oil producer, traders are worried that the unrest could hit crude shipments through the Suez Canal and Sumed Pipeline, which provide a link between Europe and oil producers in the Gulf.
The canal carries about 2.5 million barrels daily, or 2.7 percent of global supply.
Investors were also exercising caution ahead of the Wednesday release of the minutes of a July meeting of the US central bank's policy-setting Federal Open Market Committee.
The minutes are expected to provide clues as to the scale and timing of the withdrawal of the Fed's massive monetary stimulus measures.
"With speculation rife for a September taper, the minutes will be scoured through for any hints pointing towards the initial reduction amount," Chua said.