US Secretary of State Rex Tillerson arrived in Qatar Tuesday for talks on the Gulf diplomatic crisis as leaks of secret agreements between regional powers triggered fresh tensions.
Tillerson's arrival in Doha was overshadowed by the publication of pre-existing confidential agreements between Qatar and other Gulf Cooperation Council (GCC) states in which all sides had pledged to combat terror funding and avoid interference in other states.
Publication of the accords, dated 2013 and 2014, caused both sides in the deadlocked dispute to launch a fresh round of mutual accusations over ties to Islamist extremist groups.
The United States and Qatar signed an agreement on combating terrorism and its financing during a visit to Doha by US Secretary of State Rex Tillerson, his senior adviser RC Hammond told reporters.
"This is a hopeful step forward," Hammond added.
Kuwait has emerged as the main mediator in the conflict between Qatar and a group of Arab states, led by Saudi Arabia, over allegations Doha was too close to both Islamist extremists and Shiite Iran.
Riyadh agreements
The publication of documents dubbed the Riyadh agreements on Monday appears to have renewed hostility between Qatar and its neighbours.
US broadcaster CNN aired leaked papers in which Saudi Arabia, Qatar and Kuwait, and later Bahrain and the UAE had signed accords forbidding support for any opposition and hostile groups in their own nations, as well as in Egypt and Yemen.
A joint statement released by the Saudi-led bloc boycotting Qatar confirmed the documents proved "beyond any doubt Qatar's failure to meet its commitments and its full violation of its pledges".
Doha, however, maintains that the boycott is in violation of the 2013 and 2014 agreements.
A statement from the Government Communications Office said the current "siege" was "a clear violation" of the GCC's charter and the Riyadh agreements.
US interests
Tillerson's visit is the latest in a series by officials to the region, including UN diplomats and the foreign ministers of Germany, Britain and Oman.
The US and its Western allies have vast economic and political interests in the Gulf, which pumps one fifth of the world's oil supplies, houses one third of proven global crude reserves and sits on one fifth of the world's natural gas deposits.
Qatar is also home to the US military's largest air base in the region, al-Udeid. Rival Bahrain houses the US Navy Fifth Fleet.
Analysts say Tillerson's impact on the crisis largely depends on his ability to manoeuvre regional scepticism over the extent to which he in fact represents the president of the US.