Kuwait has said that Saudi Arabia is reopening its land and sea borders to Qatar in a breakthrough in a long-running dispute that has pitted Qatar against several of its Gulf neighbours.

The move comes ahead of a summit of the Gulf Co-operation Council to be held in Saudi Arabia on Tuesday.

A senior US official said an agreement to end the rift would be signed.

Saudi Arabia's embargo of Qatar 'to be lifted' https://t.co/FQaP4HYUA2

— BBC News (World) (@BBCWorld) January 4, 2021

Qatar's neighbours imposed an embargo on Qatar three and a half years ago, accusing it of supporting terrorism.

The UAE, Bahrain and Egypt joined the Saudis in maintaining the diplomatic, trade and travel embargo.

Qatar, a tiny but immensely wealthy Gulf state, has always denied supporting jihadist militancy.

The breakthrough was announced on TV by Kuwaiti Foreign Minister Ahmad Nasser al-Sabah.

Mediation efforts led by Kuwait had achieved little until recently, but in the past few months there were growing signs of a face-saving resolution to a row that has harmed all those involved, BBC Arab Affairs Editor Sebastian Usher reports.

The US administration has taken a more visible role and the senior US official said President Donald Trump's son-in-law and senior adviser, Jared Kushner, would attend the signing of the agreement on Tuesday.

The Emir of Qatar, Tamim bin Hamad Al Thani, has accepted an invitation from Saudi Arabia's King Salman to attend the summit.

A source involved in organising the summit said the Saudi decision to open its air space and land and sea borders was the confidence-building step needed to ensure the emir's attendance, BBC Chief International Correspondent Lyse Doucet reports.