Swiss and Austrian investigators have launched probes into alleged spying in hotels hosting delicate Iranian nuclear talks, with Israel denying Thursday its secret services were involved.

The revelation comes in run-up to a June 30 deadline for a historic agreement between Iran and world powers on curtailing Tehran's nuclear program in return for relief from punishing sanctions, and a day after a Russian-based security firm said a computer worm widely linked to Israel was used to spy on the negotiations.

Israel has lodged a formal protest with Bern over Swiss funding for an exhibit by an Israeli NGO critical of the army's conduct in the Palestinian territories, officials said Wednesday. 

The exhibit, which will open in Zurich later this week, is being staged by Breaking the Silence, a rights group whose members are veteran combatants who testify about the abuses they have seen or taken part in during their military service in the occupied Palestinian territories.

The European Union and Switzerland signed a major accord Wednesday that will end banking secrecy for EU residents and prevent them from hiding undeclared income in Swiss banks, the European Commission said.

The agreement deals "another blow against tax evaders, and (represents) another leap towards fairer taxation in Europe," said Pierre Moscovici, the EU commissioner for tax issues.

A Swiss man killed three in-laws and a neighbor in a town near Zurich before turning his gun on himself, police said Sunday, sending shockwaves through the normally tranquil nation.

Local police swiftly ruled out a terrorist attack, characterizing the incident as a "tragic relational drama."

Switzerland said on Wednesday it would be willing to adopt an EU migration proposal currently being debated by Brussels for the even geographical distribution of asylum seekers across Europe.

"It is high time for Europe to have a distribution ratio based on solidarity. Switzerland will join it," President Simonetta Sommaruga said during a meeting with her Austrian counterpart, Heinz Fischer, in Vienna.

The U.N. will Tuesday start hosting separate talks with rival sides and "as many stakeholders as possible" in war-torn Syria in a bid to kickstart stalled negotiations to end the four-year conflict.

United Nations peace envoy for Syria Staffan de Mistura will give a news conference around midday Tuesday, kicking off four to six weeks of "separate consultations" with different sides in Syria's four-year conflict, spokesman Ahmad Fawzi said.

Iran is determined to end the "manufactured crisis" over its nuclear program and drafting of a final deal with world powers, though hard, is progressing, Foreign Minister Mohammad Javad Zarif said Monday.

The remarks, on Zarif's official Twitter account, came two days after U.S. Secretary of State John Kerry denounced what he said was "hysteria" from opponents of an agreement, which is due by June 30.

A Swiss business delegation will go to Iran this weekend in the first such visit in 10 years to try and expand trade ties, the finance ministry said Friday.

The team, comprising executives from the pharmaceutical, green energy and services sectors, will be led by Livia Leu, who served as Swiss ambassador to Tehran between 2009 and 2013, it said.

Switzerland tops a global ranking of happiness, closely followed by Iceland, Denmark, Norway and Canada in a comprehensive study unveiled by academics in New York on Thursday.

The 2015 World Happiness Report is the third annual report that seeks to quantify and explain happiness in 158 countries as a means of influencing government policy across the planet.

Iran and major powers held a second day of talks Thursday seeking to finalize a historic deal that would make any attempt by Tehran to make a nuclear weapon extremely difficult and easily detectable.

Meeting in Vienna, Iran and the five permanent members of the U.N. Security Council plus Germany want to turn a framework accord reached in Switzerland on April 2 into a full agreement by June 30.