Hamas on Tuesday closed the offices of Gaza's only mobile telephone company after accusing it of tax-dodging, a move experts said could halt all cellular services in the Palestinian territory.

Police in the Gaza Strip, which Hamas controls, shut the offices of Palestinian telecoms provider Jawwal in Gaza City and left notices proclaiming it was "on the orders of the (Hamas) public prosecutor", an AFP correspondent said.

Oil prices extended losses in Asia Tuesday on expectations Greece will miss a key debt repayment later in the day and edge closer to a eurozone exit, analysts said. 

U.S. benchmark West Texas Intermediate (WTI) for August delivery fell 23 cents to $58.10 while Brent crude for August eased 15 cents to $61.86 in late-morning trade.

Despite claims of its imminent demise, Qatar's controversial "kafala" sponsorship system -- which critics say is a direct cause of misery and abuse for many foreign workers -- clings stubbornly to life.

On Monday, in a sign of how entrenched the issue has become, Qatar's normally quiet government used its new communications office to make a rare public statement and reassure critics that change to the system, which limits the rights of movement for foreign workers, really is on the way.

The creation of the Chinese-led Asian Infrastructure Investment Bank is a bigger coup for Beijing than its hosting of the 2008 Olympics, state-run media said Tuesday after 50 countries signed its legal framework.

China was spurred to create the AIIB after "unfair treatment" by Washington-led institutions, the Global Times said in an editorial, apparently referring to the World Bank and International Monetary Fund.

Shares in Sony plunged 8.25 percent Tuesday on dilution fears after the Japanese electronics giant announced plans to raise $3.6 billion through stock and bond sales.

The stock closed at 3,461.5 yen on the Tokyo Stock Exchange, down 8.25 percent from the previous day, while the benchmark index ended up 0.63 percent.

Switzerland's central bank was forced Monday to intervene "in order to stabilize the markets," which have tumbled over Greece's escalating crisis, the bank's chief Thomas Jordan said.

Jordan did not specify the amount spent on the intervention aimed at halting the rise in the Swiss franc -- a refuge currency -- but reiterated that the bank had always said it was ready to intervene if necessary.

Italy's finance minister on Monday played down the threat of Italy being hit by the fallout from market instability linked to the Greek crisis.

"I would not be surprised but neither would I be that concerned if there was an increase in market volatility. The European Central Bank has all the instruments at its disposal to deal with it," Pier Carlo Padoan said in an interview with Corriere della Sera.

Countries from five continents formally signed up Monday to the China-led Asian Infrastructure Investment Bank -- a potential rival to the Washington-based World Bank -- as Beijing steps up its global diplomatic and economic role.

Australia was the first country to sign the articles of association creating the AIIB's legal framework at a ceremony in Beijing's Great Hall of the People, an Agence France Presse journalist saw, followed by 49 other founding members. 

Asian equities and the euro tumbled Monday on fears Greece will crash out of the eurozone after Athens called off debt reform talks and announced a referendum on creditors' proposals next weekend, days after a repayment deadline.

Markets in mainland China plunged again, with Shanghai falling more than seven percent after losing about 20 percent from their recent peaks over the past two weeks. A weekend central bank interest rate cut was unable to offset profit-taking and a tightening of trading rules.

European nations urged Sunday their nationals to carry cash with them when vacationing in Greece as the country hurtles towards a banking crisis.

The German foreign ministry recommended that tourists "take sufficient amounts of cash" when visiting Greece, a top vacation spot for Germans, keep tabs on the evolving situation and check for any updates to its travel recommendations.