Qatar accused a Saudi-led alliance enforcing an embargo on Doha of refusing to engage with efforts it said were US-backed to resolve a crisis which entered its fourth year Friday.

Riyadh, along with the United Arab Emirates (UAE), Egypt and Bahrain cut diplomatic, economic and travel ties with Doha on June 5, 2017, insisting Qatar was too close to Iran and funding radical Islamists.

Gas-rich Qatar fiercely rejected the allegations and refused to budge on 13 demands made by its allies-turned-adversaries, including the closure of the Doha-based Al-Jazeera news network and shutting a Turkish military base in the emirate.

"There is an initiative and a positive atmosphere in cooperation with the United States -- and so far there is no response from the other side," Qatari Foreign Minister Mohammed bin Abdulrahman Al-Thani told Al-Jazeera.

Qatar has not previously confirmed US involvement in efforts to bring about reconciliation between the former allies.

The latest effort, one of several since the start of the crisis which has complicated regional travel and trade as well as separating families, was being led by Kuwait, he added.

"We hope this time there will be seriousness towards the Kuwaiti initiative with the support of the United States."

Ahead of Abdulrahman's comments, the UAE said the Gulf had changed and could not return to how it was before the rupture with Doha. 

"I do not think that the Qatar crisis, on its third anniversary, deserves comment", UAE Minister of State for Foreign Affairs Anwar Gargash wrote on Twitter.

"Paths have diverged and the Gulf has changed and cannot go back to what it was," he said.

Despite a flurry of positive signs at the end of last year, including a round of shuttle diplomacy that saw the Qatari foreign minister visit Saudi Arabia for talks, the freeze shows no sign of thawing.

"The causes of the crises are known, and the solution is also known and will come in time," Gargash said, without elaborating.