Jordan on Monday expelled Syria's ambassador over his "repeated insults" to the kingdom, drawing a swift tit-for-tat response from Damascus, which ordered Amman's top diplomat to leave.
On the battlefield, Syrian rebels made advances in the war-torn country's northwest, seizing several army checkpoints and inching closer towards taking over two major bases, according to a monitor and activists said.
In Amman, Jordanian foreign ministry spokeswoman Sabah Rafi said the government "considers the Syrian ambassador to Jordan persona non grata and has demanded he leave the country within 24 hours."
"The decision comes after Suleiman's repeated insults to Jordan and its leadership, institutions and citizens, through his meetings, writings and social media websites," she said, cited by state-run news agency Petra.
Rafi said the government in Jordan, which is hosting hundreds of thousands of refugees from the conflict across its borders, had "repeatedly warned Suleiman not to exploit Jordanian hospitality."
"Suleiman used Jordan as a platform to question its positions and make false accusations and allegations against the kingdom," she said.
"He also used Jordan to directly insult brotherly and neighbouring Arab countries and insult their leaderships."
- 'Baseless decision' -
In response to the Jordanian move, Syria said it was kicking out the Jordanian charge d'affaires in Damascus.
"The Syrian foreign ministry will order the expulsion of the Jordanian charge d'affaires to Damascus," said state TV channel Al-Ikhbariya.
It quoted the foreign ministry saying the decision came "in response to the Jordanian government's baseless decision to declare the Syrian ambassador to Amman persona non grata."
Jordan recalled its ambassador to Syria, Omar al-Amad, in early 2011 after pro-Syrian regime protesters attacked Amman's embassy in Damascus.
Last June, Jordanian Foreign Minister Nasser Judeh told Suleiman to stop criticising the country or risk expulsion.
The warning came after Suleiman attacked Jordan for hosting a meeting of the anti-regime "Friends of Syria" group, which includes Jordan, calling it "a meeting of Syria's enemies".
He also sharply criticised Jordan after the United States decided last year to send the kingdom a Patriot missile battery, F-16 fighters and troops to counter the threat posed by Syria's civil war.
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He has in the past described the estimated 600,000 Syrian refugees in Jordan as "terrorists."
Amman has repeatedly expressed fears that the brutal war in neighbouring Syria could spread and warned of the impact of jihadists among anti-regime fighters.
Damascus, for its part, accuses Amman of backing the three-year uprising against President Bashar al-Assad by training and arming rebels.
Jordan denies the charges, stressing it has tightened its border and jailed dozens of militants trying to cross illegally.
- Fresh rebel advance -
On the ground, rebels advanced in Idlib province as Al-Qaeda's Syria branch, the Al-Nusra Front, claimed responsibility for two car bomb attacks that killed 12 people a day earlier in the central city of Homs.
The rebels and their jihadist Al-Nusra Front allies took over "the Salam checkpoint west of the town of Khan Sheikhun after fierce battles against regime troops", the Syrian Observatory for Human Right said.
The Syrian Revolution General Commission (SRGC), a network of activists across the country, said the Salam checkpoint was "the last regime position in the Khan Sheikhun area," in the south of Idlib province.
Khan Sheikhun "is now completely liberated," the London-based group said.
While rebels have been losing ground in the centre of Syria, they have in recent weeks been making steady progress in Idlib and north of Hama.
The Observatory said opposition fighters have blocked access to the highway linking the south of Idlib province to rebel-held Morek in the north of neighbouring Hama province.
It said the latest advance brings rebels closer to taking over the Wadi Deif and Hamidiyeh army bases in the area, which opposition fighters have besieged for more than a year.
Meanwhile, at least three people were killed in an aerial barrel bomb attack in the Aleppo district of Bustan al-Qasr, as the regime kept up its bid to reclaim opposition-held areas of Syria's second city, according to the monitoring group.