Qatar’s leading opposition figure, Sheikh Saud bin Nasser Al Thani, said he was heading to Doha on Friday to act as mediator in bridging the growing rift between Qatar and its neighbours.

Sheikh Saud said he was invited by Sheikh Joaan bin Hamad bin Khalifa Al Thani, brother of the emir of Qatar.

Sheikh Saud, who is a member of the Qatari ruling family, told the London-based newspaper Al Hayat newspaper: “My visit to Doha will discuss a compromise formula to break the current crisis that will strain the relationship between Qatar and its sister countries from the Gulf states and the Arab countries.”

He also announced that he was preparing to launch a political party in opposition to the regime headed by Sheikh Tamim bin Hamad Al Thani and warned the rulers about pursuing “policies aimed at breaking the unity of the Arab ranks”.

“We have kept quiet over the irrational behaviour of the regime in Qatar,” he told the Egyptian news website Youm7. “Because of this systematic behaviour towards the breaking of Arab ranks and aborting projects on which we were unified, we decided to speak with the people of the Arab world in general and the Qatari people in particular, and I will seek to establish an opposition party to be based in London.”

Sheikh Saud has become increasingly vocal about his concern over deteriorating relations between Qatar and the rest of the Arab world. On Twitter, he urged the emir to “return to the right path”.

In another tweet he wrote: “We hoped that foreign policy would change and our hopes were disappointed after you joined forces with Iran against your brothers and set up terrorist groups and published electronic battalions to beat your opponents. Sheikh Tamim, Qatar has become a source of financing terrorism and an export port of extremist thought. ”

Sheikh Saud has already issued an apology to the Gulf states, Egypt and Yemen but he told Al Hayat he would press for Qatar to issue a formal apology to Saudi Arabia, the UAE and Bahrain.

The mediation would address several points, Sheikh Saud said.

These would include suspending the activity of the executive office of the first lady of Qatar, Sheikha Mozah Al-Misnad; freezing the alliance between Qatar and Iran; ceasing all support to operations in Libya, Egypt, North Africa and Sudan, and the expulsion of all extremist elements hosted by Qatar.

If the terms are agreed, the prime minister of Qatar, Abdullah Nasser Al Thani, will sign a memorandum of understanding on behalf of the Qatari government, promising to set up the Ahmed Bin Ali Development Foundation.

Sheikh Saud stressed that he was speaking for all who oppose current Qatari attitudes towards its regional neighbours. His intentions were not opposition for its own sake, but to prevent Qatar from breaking apart.

The meeting would last only a few hours, he added, as he would be leaving Doha the same evening.

The rift between Qatar and the rest of the GCC arises from inflammatory comments attributed to the emir, in which he apparently praised Iran, Hamas and Hizbollah and implied he needed protection from neighbouring nations. However, Doha insisted the emir was a victim of hackers and had sought outside help to prove it. An official source said an FBI team has been in Doha for the past week investigating the security breach.

Two other unnamed countries are also helping with the probe, the source added.

* with additional reporting from Agence France-Presse