Major oil producers began talks in Qatar on Sunday to try to reach a deal on capping production to boost prices, despite Iran's absence.

Cuban President Raul Castro vowed Saturday never to pursue "privatizing formulas" or "shock therapy," setting the tone for a Communist Party congress convened to review progress in revamping the island's Soviet-style economy.

"Cuba will never permit the application of so-called shock therapies, which are frequently applied to the detriment of society's most humble classes," he said in a speech opening the congress, which only happens every five years and stretches on for several days.

The international community is not sticking to its promises to lift sanctions on Iran in the wake of the nuclear deal, the country's central bank governor said Friday.

The International Monetary Fund said Friday that the fiscal projections underpinning Greece's proposals for moving ahead in its bailout program are not realistic.

Poul Thomsen, director of the IMF's European Department, raised questions about the forecast that Greece could maintain a 3.5 percent budget surplus for years as part of its plan for debt relief from European Union creditors.

A new multilateral lender set up by the BRICS nations has approved its first set of loans valued at $811 million for renewable energy projects in four of its member countries, according to the bank.

Iran's oil minister will not join an Iranian delegation at a meeting this weekend of major crude producers aimed at negotiating a production freeze, the oil ministry said on Friday.

Greek Prime Minister Alexis Tsipras on Friday said the IMF should stop tinkering with the country's latest bailout with European creditors, blaming the global lender for causing a delay in talks.

The IMF has worked with the EU on two previous Greek bailouts but said it would not participate in the latest plan without credible reforms and an EU agreement to ease Greece's debt burden.

Europe's top economies called for a crackdown on tax havens and urged G20 countries to rip away the secrecy protecting shell companies, as the Panama Papers scandal claimed Spain's industry minister as the latest political victim.

In the strongest reaction yet to the leaked Panama Papers, the finance ministers of Britain, France, Germany, Italy and Spain proposed a blacklist of havens like Panama if they failed to share corporate registry data.

Major oil producers meet this weekend to try to negotiate an output freeze to drain crude oversupply and boost prices, but doubts remain over whether Iran will join any accord.

Qatar said Thursday there was an "atmosphere of optimism" that an agreement would be reached at this weekend's crunch meeting of the world's major oil producers in Doha.

In a statement released through the official Qatar News Agency, the Qatari energy ministry said it was increasingly hopeful of a deal.