Oil prices rose on Monday, extending recent gains, building on three weeks of higher prices and reversing earlier losses from traders taking profits.
Front-month Brent crude was trading at $45.45 per barrel at 1302 GMT, up 34 cents from its last settlement.
U.S. West Texas Intermediate (WTI) futures were up 17 cents at $43.90 a barrel.
ABN Amro chief energy economist Hans van Cleef said that prices were reflecting the anticipation of the rebalancing of supply and demand.
"Meaning that demand will continue to rise and supply will be hit, especially non-OPEC," van Cleef said.
ABN Amro forecasts oil prices of $55 per barrel by year end.
Market data shows that the amount of open positions betting on rising WTI prices rose to levels last seen in June 2015 last week, while bets taken out in expectation of falling prices fell close to 2016 lows.
Traders also said oil fell on a jump in the dollar on Friday against a basket of other leading currencies on expectations that Japan will further extend its aggressive monetary easing through negative interest rates.
A stronger dollar, in which oil is traded, makes fuel imports for countries using other currencies more expensive, potentially hitting demand.
The dollar index was trading 0.3 percent lower on Monday.
"The oil market is likely to tighten noticeably in the second half of the year, as U.S. oil production is meanwhile declining significantly,"
Commerzbank said in a daily note.
The U.S. rig count fell for a fifth straight week on Friday to levels last seen in November 2009.
Barclays bank analysts said they were "not yet convinced that prices will remain here or go even higher", however, as fundamentals remained weak.
"Still-elevated inventory levels, the return of some disrupted supply, further boosts to Saudi and Iranian supply, and increased non-OECD product exports all have the potential to move prices lower over the next several months, especially if broader macro sentiment shifts," it said.
Indonesia's governor to the Organization of the Petroleum Exporting Countries said on Monday that oil at $45 a barrel was "not bad" and that there would be no urgency to freeze output levels if crude remained at that price.
(By Sarah McFarlane, Additional reporting by Henning Gloystein in Singapore)