John Kerry, the US secretary of state, has held meetings with senior officials of Arab Gulf states to reassure them over last month's nuclear deal between world powers and Iran.
Kerry met the emir of Qatar on Monday morning in advance of a separate meeting with the foreign ministers from the Gulf Cooperation Council (GCC).
He later held news conference with Qatar's foreign minister, Khalid Al Attiyah.
At the start of Kerry's meeting with GCC foreign ministers, Al Attiyah enumerated a number of other issues including the ongoing conflict in Yemen and the pursuit for an independent Palestinian state.
Before Kerry's arrival, foreign ministers of the GCC held a preparatory meeting in Doha on Sunday.
The Gulf Arab states have publicly welcomed the deal reached last month in Vienna but many have expressed private reservations.
Al Jazeera's Hashem Ahelbarra, reporting from Doha, said that GCC officials are expected to "voice their concerns with the Iran deal".
"This is quite a delicate moment for the Gulf countries," he said. "They are worried that Iran might finally be able to foster ties with the West, get the sanctions lifted and pursue an active role in the region."
Our correspondent said that there are concerns that Iran continues to back the Assad regime in Syria and the Houthi rebels in Yemen.
Kerry is also expected to discuss the fight against the Islamic State of Iraq and the Levant (ISIL) group in Syria and Iraq.
Sergei Lavrov, Russian foreign minister, also arrived separately in Doha on Sunday night with plans to hold a three-way meeting with his Saudi Arabian counterpart and Kerry on Monday morning.
The Russian foreign ministry said Lavrov was visiting Qatar to discuss peace moves in Syria, Yemen and Libya, international consolidation against ISIL, stability in the Gulf, and bilateral relations between Russia and Qatar.
On Sunday, Kerry stopped in Cairo for meetings with his Egyptian counterpart Samed Shoukry and Egyptian President Abdel Fattah el-Sisi where he said US-Egyptian relations were returning to a "stronger base" in bilateral ties despite tensions and human rights concerns.
The development comes two days after the US delivered eight F-16 fighter jets to Egypt as part of a military support package.
In talks with Shoukry, Kerry also raised the issue of human rights and pressed Egypt on the arrests of dissidents and journalists and mass trials.
|Kerry held talks with the emir of Qatar on Monday morning in Doha as part of a busy schedule [Reuters]
Source: Al Jazeera and agencies