Oil prices inched up today but have held near a one-week low ahead of a joint OPEC and non-OPEC meeting later that may address rising output in Nigeria and Libya.

London Brent crude for September delivery was up 12 cents at $48.18 a barrel by 7.51am Irish time.

The contract settled down $1.24, or 2.5%, on Friday after a consultancy forecast a rise in OPEC production for July.

NYMEX crude for September delivery was up 7 cents at $45.84 a barrel.

Ministers from the Organization of the Petroleum Exporting Countries (OPEC) and other non-OPEC producers will meet in the Russian city of St Petersburg to review market conditions and examine any proposals related to their pact to cut output.

Sources familiar with the talks said the meeting may recommend a conditional cap on production from Nigeria and Libya - two OPEC members so far exempt from output cuts - although some analysts were deeply sceptical the group would make such a move.

"Output cuts by Libya and Nigeria would be next to impossible considering Libya was just re-emerging from the civil war, for example," said Kaname Gokon, strategist for commodities brokerage Okato Shoji in Tokyo.

OPEC and some non-OPEC states including Russia agreed last year to cut production by 1.8m barrels per day (bpd) in a deal that has been extended to March 2018.

Russian Energy Minister Alexander Novak said Libya and Nigeria should cap output when their output stabilizes, the Financial Times reported.

Kuwait's oil minister, Essam al-Marzouq, said on Saturday that compliance was good with oil production cuts by OPEC and non-OPEC countries and that deeper curbs were possible.

Meanwhile, OPEC Secretary General Mohammad Barkindo said on Sunday that a rebalancing of the oil market is progressing more slowly than expected, but will speed up in the second half of 2017.

"Oil looks likely to remain stuck in a tight range, as investors await any signs that OPEC will intensify its effort to rebalance the market," ANZ bank said.

The United States is considering financial sanctions on Venezuela that would halt dollar payments for the country's oil, sources told Reuters, which could severely restrict the OPEC nation's crude exports.