Brent North Sea crude for delivery in November jumped $1.59 to $105.53 a barrel in London midday deals.
New York's main contract, West Texas Intermediate (WTI) for November, rallied $2.18 to $82.42.
"Oil prices have recovered quite a bit," said Commerzbank analyst Carsten Fritsch.
"The main reasons are a change of sentiment on financial markets, reflected in rising equity markets and a somewhat weaker US dollar.
"The downside risks for the economy and oil demand have not disappeared overnight, so a renewed price fall cannot be ruled out," he added.
Greek Prime Minister George Papandreou was to meet German Chancellor Angela Merkel for talks Tuesday on containing a eurozone debt crisis which US President Barack Obama said is scaring the world.
Stock markets around the globe rallied sharply on hopes European leaders would finally get a grip on the long-running crisis threatening the euro project, even if analysts cautioned such euphoria could prove short-lived.
What the stars mean:
★ Poor ★ ★ Promising ★★★ Good ★★★★ Very good ★★★★★ Exceptional