Bahrains decision to withdraw its ambassador from Qatar on 5 March is likely to be a further setback to the long-delayed Friendship Causeway link the two countries have planned for more than a decade.
The estimated $4bn project, which is one of the most ambitious infrastructure schemes in the region, involves building a 40-kilometre-long causeway that will create a road and rail link between northern Qatar and Bahrain.
The causeway was also one of the major new infrastructure schemes Qatar included in its bid document for Fifas 2022 World Cup, with officials at the time saying the visitors to the tournament will be able to stay in Bahrain and travel to matches across the causeway.
Last year, it appeared the project may be invigorated when a consultancy firm was commissioned to review the basic engineering designs of the planned bridge, following the resumption of talks between Manama and Doha. Those talks have now ended.
First unveiled in 1999, the causeway was approved by both the Bahraini and Qatari governments in 2005.
A consortium of state-owned developer Qatari Diar Real Estate Investment Company and French contractor Vinci Construction Grand Projects. Germanys Hochtief, Athens-based Consolidated Contractors Company (CCC), Dredging International from Belgium, and the local Middle East Dredging Company (Medco) started working on the link in 2008.
US-based engineering and construction company KBR was managing the project.
The scheme was subsequently hit with delays and the consortium demobilised in 2010.
Original designs for the project comprised a 40km dual carriageway featuring 22km of bridges and viaducts and 18km of embankments and two 400-metre cable-stayed bridges. The causeway will connect Ras Ashairij on the west coast of Qatar to Askar on the east coast of Bahrain.
If built, the crossing is expected to cut the journey time between the two countries, which involves a detour through Saudi Arabia, from five hours currently to just 30 minutes.
Bahrain, together with Saudi Arabia and the UAE, said on 5 March that they had withdrawn their ambassadors from Qatar because Doha has failed to implement an agreement it signed with the GCC states, which committed it to the principles of non-interference in the internal affairs of any of the GCC countries. It says the agreement was signed by Sheikh Tamim bin Hamad al-Thani in Riyadh on 23 November 2013.