London — Oil prices rose on Wednesday, back towards five-month highs hit the previous day as oil cartel Opec production cuts and US sanctions on Iran and Venezuela continued to tighten supply, although economic worries increased.

International benchmark Brent futures were at $70.92 a barrel at 9am GMT, up 31c, or 0.44%, from their last close. US West Texas Intermediate (WTI) crude oil futures were at $64.33 a barrel, up 35c, or 0.55%, from their last settlement.

Oil markets have tightened this year because of US sanctions on oil exporters Iran and Venezuela, as well as supply cuts by Opec and some non-affiliated producers including Russia, a group known as Opec+.

Brent and WTI crude oil futures have risen by about 30% and 40%, respectively, since the start of the year.

“The global oil market is clearly moving back towards balance thanks to Opec+ production cuts,” ING bank said. The Dutch bank said the reduction was not only down to voluntary supply cuts, which the group started this year to prop up prices, but also involuntary curbs from Venezuela and Iran — which are exempt from the Opec cut pact — due to US sanctions.

“Declines from these two exempt countries account for almost 47% of the reduction seen from Opec,” ING added.

But Russia’s role in the pact came into focus after a senior Russian official signaled that Moscow might seek to raise output, though President Vladimir Putin indicated on Tuesday that current prices suited Russia.

“The Russian camp is increasingly coy about extending supply cuts. Suffice to say, this may throw a spanner in the works for a sustained price recovery,” said PVM analyst Stephen Brennock.

Not all regions are in tight supply, however.

US crude stocks rose by 4.1 -million barrels in the week to April 5 to 455.8-million barrels, data from industry group the American Petroleum Institute (API) showed on Tuesday, though petrol and distillate inventories fell more than expected.

But in its third downgrade on global growth since October, the International Monetary Fund (IMF) warned on Tuesday that the global economy was slowing more than expected and that a sharp downturn may be looming. Slower growth would undermine fuel demand and could put a cap on prices.

The IMF said the global economy would likely grow 3.3% this year, the slowest since 2016. The forecast cut 0.2 percentage points from the IMF’s outlook in January.