Iranian Foreign Minister Ali Akbar Salehi is to visit Turkey on Tuesday for previously unscheduled talks expected to focus on Syria and a group of Iranians seized by rebels there, an Iranian diplomat in Ankara said.
Iran has stood by its ally Syria despite the growing international pressure on Assad, while Turkey has been among the Syrian president's fiercest critics, demanding that he stand down to defuse a 17-month uprising against his rule.
The Iranian diplomat said Salehi was expected to arrive in the afternoon and leave later on Tuesday.
"It is expected that the talks will take up the Syrian issue and the situation of the pilgrims kidnapped in Damascus, as well as bilateral issues," the diplomat told Reuters.
Jalili, who arrived in Syria after wrapping a visit to Lebanon, was scheduled to meet Assad and Syrian Deputy Foreign Minister Ahmad Arnous, IRIB said. Jalili planned to hold a press conference at Iran's embassy in Damascus on Tuesday, it said.
Jalili acts as the representative of Iran's ultimate authority, Supreme Leader Ayatollah Ali Khamenei, and is also Iran's chief negotiator in Tehran's dispute with Western powers over its nuclear programm.
Khamenei decides Iran's foreign policy.
"We have always said that the solution to the problem in this country is democracy, which cannot be achieved through the export of arms and bloodshed," Jalili, referring to Syria, was quoted as saying by the Iranian Students' News Agency during a meeting with Lebanese Foreign Minister Adnan Mansour.
Iran has asked Turkey, as well as Qatar, to help secure the release of 48 Iranians seized by rebels in Syria on suspicion of being military personnel, though Tehran says they are pilgrims.
A Syrian rebel spokesman said on Monday that three of the Iranians had been killed in a government air strike in Damascus and warned the rest of them would be executed if the attacks did not stop. There has been no word of their fate since then.
Syrian rebels fighting to topple Assad accuse Iran of sending fighters from its Revolutionary Guard to help Assad's forces put down the uprising.
Tehran denies the charge and says the group was on a religious pilgrimage to Syria. Iranian media said on Saturday that the 48 had been abducted from a bus in Damascus, the latest in a string of kidnappings of visitors from the Islamic Republic.
Iranian Deputy Foreign Minister Hossein Amir-Abdollahian on Monday blamed Turkey, the US and Qatar for the kidnappings, and Iran summoned a diplomat inSwitzerland's embassy in Tehran, which looks after American interests in the absence of a US embassy there, over the kidnappings, Iranian media reported.
"In the name of Islam, some of these governments have launched killings and even treat Iranian pilgrims in Syria with violence. These crimes are not something the Iranian nation will disregard," Larijani said in a speech in parliament aired on Iranian television. "The American regime and some countries in the region are responsible for these crimes. And they will receive their response in turn."
Tehran has accused Turkey and Qatar of helping rebels fighting to topple Assad. Several Iranians previously abducted in Syria have been released to Turkish authorities before returning to Iran.