King Salman of Saudi Arabia has said that an agreement has been reached with Egypt to build a bridge over the Red Sea connecting the two countries.

The monarch made the announcement in televised comments on Friday - the second day of his visit to Cairo - after meeting Egyptian President Abdel Fattah el-Sisi, and before representatives of the two countries began signing investment deals.

"I agreed with my brother, his Excellency President Abdel Fattah el-Sisi, to build a bridge connecting the two countries," Salman said.

"This historic step to connect the two continents, Africa and Asia, is a qualitative transformation that will increase trade between the two continents to unprecedented levels."

It was not mentioned where the bridge would be built, but at the closest point - Nabq, just north of Sharm el-Sheikh, in Egypt, and Ras Alsheikh Hamid, in Saudi Arabia - the two countries are 16km apart.

The plan to build a joint bridge over the Red Sea at the entrance of the Gulf of Aqaba has been in the pipeline for several years.

Earlier proposals suggested the causeway would feature a railway line in parallel with the road lanes, integrating both country's proposed high-speed railway systems. In that plan, the causeway would pass through Saudi's Tiran Island, which would serve as a connection between the two countries.

Sisi, who minutes before the announcement had presented the king with the ceremonial Nile Collar, suggested the name "King Salman bin Abdel Aziz Bridge".

"The unique quality of the relations between Egypt and Saudi Arabia, the extent to which they are strong and deep-rooted, will allow us to face mutual challenges," Sisi said.

"Our cooperation will certainly allow us to resolve all of our regional crises, such as in Palestine, Yemen, Libya and Syria."

Notes from our reporter

The Saudi monarch's visit is about both politics and economics.

For King Salman, it is about showing that Saudi Arabia and Egypt would stand together against outside interference, by which they mean Iran and its ambitions in the region.

For Egyptians, much more is at stake: The two countries are signing agreements including a multibillion-dollar deal whereby Saudi Arabia will finance Egypt's oil needs for the next five years and previous estimates for the bridge suggest a cost between $3bn and $4bn.

Saudi Arabia and other Gulf states have provided Sisi with important support since he came to power in 2013. But this package from Saudi Arabia to Egypt dwarfs all previous agreements - Mohamed Vall