Opec warned that the world remains awash with crude ahead of a crunch meeting in Doha between cartel members and other major producers to discuss a production freeze to boost the oil price.
Oil reached a 2016 high above $43 a barrel, supported by hopes that an upcoming meeting of oil producers will agree steps to tackle a supply glut.
Qatar said on Tuesday that it has invited Iran to join talks among the world's top oil producers next month on implementing a proposed output freeze to stabilise plummeting prices.
Saudi Arabia is "not prepared" to cut oil production, its foreign minister said, after the top exporter agreed with Russia to freeze output if major rivals follow.
Saudi Arabia's oil minister Ali al-Naimi discussed cooperation between OPEC members and other oil producers to stabilise the global oil market with his Venezuelan counterpart on Sunday, state news agency SPA reported.