A top diplomat on Friday condemned the move by the Gulf state of Qatar to let Syria's opposition open an "embassy" in Doha, calling the decision "hasty and irrational," Iran's official IRNA news agency reported.

"Qatar's theatrical act in giving the Syrian embassy to a group which is unelected is both hasty and irrational," the deputy foreign minister in charge of Arab and African affairs, Hossein Amir Abdollahian, was quoted as saying.

A mortar attack that killed 15 students at Damascus University marks a rebel escalation in the Syrian capital ordered by foreign governments, Information Minister Omran al-Zohbi said on Friday.

"The terrorists' mortar attacks on residential areas, schools, universities and hospitals is the result of foreign orders to stage a full-scale escalation," Zohbi told state news agency SANA.

A senior official for the 2022 Qatar World Cup again downplayed suggestions that the tournament should be moved from the fierce heat of summer for player and fan safety.

Hassan al-Thawadi, general secretary of the Qatar 2022 supreme committee, told the Associated Press on Friday "we always knew about it ... we know there is an issue with the heat."

The Syrian opposition opened in Qatar on Wednesday its first "embassy," a day after opponents of President Bashar Assad were given Damascus's seat at the Arab League.

Opposition chief Ahmed Moaz al-Khatib and Qatari State Minister for Foreign Affairs Khaled al-Attiya inaugurated the representative office dubbed the "Embassy of the Syrian National Coalition".

The case of the nine abducted Lebaese pilgrims in Syria's Aazaz was the main topic of discussions between President Michel Suleiman and Emir of Qatar Sheikh Hamad bin Khalifa al-Thani on Wednesday.

Suleiman and al-Thani also tackled the latest developments in the Arab countries and the bilateral ties between the two countries.

The closing statement of the Doha Arab Summit called on Tuesday for providing support to the Lebanese military institution, urging also the adoption of the cabinet's plan for rescuing Syria's refugees.

“We reiterate our full support to Lebanon and to its cabinet and we pledge to preserve the country's security and stability,” the closing statement said.

President Michel Suleiman on Tuesday called on the Arab states to “share the burden” of hosting the Syrian refugees and urged them to seek the release of nine Lebanese pilgrims abducted by an armed group in the Syrian town of Aazaz.

“The number of Syrian refugees has surged and it is now equivalent to one quarter of Lebanon's population. Although the Lebanese state has decided not to close the border, the situations indicate that the security problems will increase and this requires a serious discussion in order to find a solution to this aggravating problem in a country based on delicate checks and balances,” Suleiman said in his address at the Arab Summit in Doha.

Arab League leaders gathered for an annual summit in Doha on Tuesday gave member states the "right" to offer Syrians all means of self-defense, including arms supplies.

The Arab summit affirms the "right of every state to offer all forms of self-defense, including military, to support the resistance of the Syrian people and the Free Syrian Army," a resolution said.

The families of the nine pilgrims abducted in Syria's Aazaz threatened on Tuesday to escalate their measures at beginning of April if the case wasn't resolved.

Protesters held banners criticizing Lebanese authorities for failing to release the men.

Afghan President Hamid Karzai is to visit Qatar to discuss the proposed opening of a Taliban office there as a prelude to possible peace talks, the foreign ministry said Sunday.

Until earlier this year, Karzai rejected the idea of a Taliban office in Qatar because of fears that his government would be frozen out of any deal between the United States and the militants.