By Stephen Kalin
RIYADH (Reuters) - Bahrain and Qatar traded barbs over the Qatari emir's decision not to attend a Gulf Arab summit in Saudi Arabia on Sunday, an absence that suggests a rift between Doha and three Gulf Arab states is unlikely to be resolved soon.
Qatar sent its state minister for foreign affairs to the annual one-day summit, which is overshadowed by the economic and diplomatic boycott of Doha since mid-2017 by Saudi Arabia, the United Arab Emirates, Bahrain and Egypt over allegations Doha supports terrorism, which Qatar denies.
"Qatar's emir should have accepted the fair demands (of the boycotting states) and attended the summit," Bahraini Foreign Minister Sheikh Khalid bin Ahmed Al Khalifa said in a tweet.
In response, Ahmed bin Saeed AlRumaihi, director of the information office at Qatar's foreign ministry, said: "Qatar can make its own decisions and had attended (last year's) Kuwait summit while the leaders of the boycotting countries did not."
The Gulf Cooperation Council's (GCC) summit of six member states opened in Riyadh as Saudi Arabia faces international pressure over the murder of journalist Jamal Khashoggi in early October at the kingdom's Istanbul consulate.
Saudi Arabia's King Salman opened the gathering, urging fellow member states Kuwait, Oman, Bahrain, the UAE and Qatar to maintain a united front against Iran and terrorism.
"This requires all of us to maintain our countries' gains and to work with our partners to preserve security and stability in the region and the world," he said in a speech.
Kuwaiti Emir Sheikh Sabah Al-Ahmad Al-Jaber al-Sabah, who has tried unsuccessfully to mediate the Qatar row, then called for an end to media campaigns he said threatened regional unity.
A closed-door session is expected to focus on oil politics, security issues including Yemen's war, and the row with Qatar, which says the trade and transport boycott aims to curtail its sovereignty.
Doha last week abruptly announced it was exiting the oil exporters' group OPEC after 57 years to focus on gas, in an apparent swipe at the bloc's de facto leader Saudi Arabia..
Saudi Arabia has resisted U.S. pressure to restore ties with Doha following Khashoggi's murder, an act that drew condemnation and scrutiny of Riyadh's assertive regional policies.
A U.S. State Department official on Sunday urged Gulf states to mend fences to confront Iran and help enable a proposed new Middle East security alliance that would include the Gulf bloc, Egypt and Jordan.
"We'd like to see that unity restored, not on our terms, but on terms of the countries that are involved," Timothy Lenderking, Deputy Assistant Secretary for Arabian Gulf Affairs, told reporters at a security forum in the UAE capital Abu Dhabi.
While the boycotting states insist the row is not a priority for them and that the GCC remains valid, Doha has said the dispute harms regional security by weakening the bloc.
Kuwait's ties with Riyadh are also strained over control of shared oilfields in the so-called Neutral Zone, further weakening unity of the GCC which was set up in 1980 as a bulwark against larger neighbours Iran and Iraq.
(Additional reporting by Alexander Cornwell in Abu Dhabi, Tuqa Khalid in Dubai and Marwa Rashad in Riyadh; Editing by Ghaida Ghantous and Andrew Roche)