Rocketing housing costs in Britain's capital have fueled a surge in Londoners seeking cheaper accommodation on boats, with increased numbers putting pressure on the city's historic network of rivers and canals.

The picturesque lifestyle of sleeping in a colorfully painted narrowboat or barge can seem tempting, especially when buying one can cost a fraction of the price of bricks and mortar.

Eurozone nations showed the "political will" to help Greece reach a bailout deal at emergency talks in Brussels Tuesday despite a referendum that rejected creditors' terms, new Greek finance minister Euclid Tsakalotos said.

Tsakalotos, who replaced maverick Yanis Varoufakis in the job on Monday, told reporters there had been "progress" in meetings with his 18 counterparts from the single currency and added there was "political will to give Greece a new chance."

European leaders accused Greece at an emergency summit Tuesday of failing to produce concrete proposals for a new bailout to keep it in the euro after Greeks defiantly voted against further austerity.

Greece's leftist prime minister Alexis Tsipras faced his 18 eurozone counterparts for the fraught talks in Brussels, while at home Greek banks remain closed and fears grow that the economy could implode.

The British government announced plans on Tuesday to allow shops to open longer on Sundays to compete with online shopping and global tourist destinations like Paris and New York.

Finance Minister George Osborne said he wanted to give mayors and local authorities the power to decide Sunday shopping hours in his budget, which will be unveiled on Wednesday.

Hated in Athens and brushed off by the Europeans, the International Monetary Fund approaches the next round of negotiations with Greece in a delicate position.

The global crisis bank is anxious to craft a compromise, but also under pressure to recover the billions it has lent to the country.

British bank HSBC fired six staff after they filmed a mock Islamic State-style execution video during a team-building day out and posted footage online, a spokesman confirmed on Tuesday.

The bank described the video, showing staff members in balaclavas holding a fake knife over a kneeling man in an orange jumpsuit, as "abhorrent".

France can't take the risk of Greece leaving the eurozone, which would have an effect across the globe, the prime minister said on Tuesday, adding that the basis for a deal with Athens was there.

"France is convinced that we can't take the risk of Greece leaving the eurozone," a move that would affect economies across the globe, Manuel Valls told French radio. "The basis for a deal exists... There is no taboo subject when it comes to (Greek) debt, on the restructuring."

Greek Foreign Minister Nikos Kotzias on Monday ruled out his country's exit from the EU and called for calm after Greek voters rejected bailout terms of international creditors.

"Europe without Greece? It's a joke," the visiting foreign minister told Israel's private Channel 2 television.

The White House urged Greece and EU leaders Monday to find a compromise to keep the cash-strapped country in the eurozone, after Greeks voted resoundingly to reject an austerity-based bailout.

"The referendum is over, but our view here at the White House remains the same," said spokesman Josh Earnest.

Greek banks will remain closed on Tuesday and Wednesday with limits on daily withdrawals unchanged, officials said on Monday as the European Central Bank maintained its liquidity assistance to the nation's beleaguered lenders.

"Until Wednesday evening we continue as things stand today," said Louka Katseli, chairwoman of the National Bank of Greece.