Saudi Arabia opposed Egypt joining the Mecca Joint Defence Agreement signed with Turkey and Pakistan last week, despite Ankara's push for Cairo to be included in the pact, three Saudi sources familiar with the discussions told Middle East Eye.

One of the sources, a former senior adviser to the Saudi monarchy, said Riyadh did not want Egypt to join the agreement "at least for now".

All three sources, however, who spoke on condition of anonymity due to the sensitive nature of the issue, said the Saudi position was driven by a growing frustration with President Abdel Fattah el-Sisi's government and a belief in Riyadh that Egypt no longer offered the strategic or military value it once did.

The Mecca Joint Defence Agreement, which was signed in the Holy Muslim city of Mecca on Friday, commits Saudi Arabia, Turkey and Pakistan to regard an armed attack against any one of the three countries as an attack against all three.

Saudi officials have described it as a mechanism to strengthen joint defence capabilities, despite the agreement being vague on operational mechanisms, specific triggers, and how joint military assistance would actually be executed in a crisis.

According to the sources, the Saudi decision to oppose Egypt's entry was due to simmering tensions between Riyadh and Cairo.

They said that Saudi Arabia was the biggest financial supporter of Sisi's government after he seized power in a 2013 coup, initially spending around $25b to shore up Cairo's flagging economy, but Riyadh had become frustrated by what it regards as a lack of reciprocal support on key security issues.