U.S. Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif have wrapped up three days of talks over Iran's nuclear program, as a deadline for a framework deal looms.
Zarif said on March 4 that progress was made during the talks in the Swiss resort of Montreux, but added that "a lot of work remains."
Kerry told reporters, "From the beginning, these negotiations have been tough and intense and they remain so."
"The purpose of these negotiations is not to get any deal, it's to get the right deal, one that can withstand scrutiny," he added.
The secretary of state said he will have his next meeting with Zarif on March 15 and that he won't be distracted from the talks by external factors or politics.
The United States and five other powers -- Britain, China, France, Germany, and Russia -- are seeking a deal with Iran under which Tehran, in exchange for sanctions relief, would limit its nuclear program.
Western nations fear Iran's nuclear activities could lead to the development of nuclear weapons, allegations which the Islamic republic rejects.
The negotiating sides have set an end-of-March deadline for a framework agreement and a June 30 deadline for a full deal.
Kerry will fly later in the day to Saudi Arabia to ease Gulf Arab concerns about a deal with Iran.
An unidentified U.S. official said he will meet his French, German, and British counterparts on March 7.
On March 3, Israeli Prime Minister Benjamin Netanyahu warned that such a deal could "pave Iran's path to the bomb" rather than block it.
Reacting to Netanyahu's address to U.S. Congress, President Barack Obama said the prime minister had offered no viable alternative.
An Iranian Foreign Ministry spokeswoman dismissed Netanyahu's speech as "boring and repetitive" and "part of the hard-liners' election campaign in Tel Aviv," IRNA reported.
Also on March 4, the United Nations' nuclear watchdog said its representatives will meet Iranian officials in Tehran on March 9 to discuss technical details of Iran's nuclear work.
The International Atomic Energy Agency (IAEA) said the delegation will be headed by its chief inspector, Tero Varjoranta.
The last such technical meeting dates back to November 2014.
IAEA Director-General Yukiya Amano told the IAEA's board of governors in Vienna on March 2 that Iran had still not handed over key information to his staff.
Yukiya said the agency could not "conclude that all nuclear material in Iran is in peaceful activities."
Amano said the IAEA remained ready to accelerate the resolution of all outstanding issues, adding that "this process cannot continue indefinitely."