Iraq's Prime Minister Nuri al-Maliki challenged Syria on Thursday to explain why it shelters armed groups that Iraq blames for staging bombings in its territory, Reuters reported.
In a statement that appeared to ratchet up rhetoric in an increasingly ugly row between the two countries, Maliki also said "neighboring countries" could no longer use the excuse of Iraq's occupation by U.S. forces for backing insurgents, since U.S. troops left Iraqi cities in June.
"Why must they insist on sheltering the armed organizations and those wanted by Iraqi courts and Interpol on Syrian lands?" Maliki was quoted by his office as saying.
Baghdad last week demanded that Damascus hand over two alleged masterminds of bombings in the Iraqi capital that killed almost 100 people last month, triggering a row that saw both countries recall their ambassadors for consultations.
Iraq's Shi'ite-led government has blamed supporters of Saddam Hussein's outlawed Baath party, and Sunni Islamist al Qaeda, for recent attacks, and says Baath party leaders plotted the bombings from Syria.
Government officials later broadcast a video of what they said was a confession by a suspected al Qaeda militant claiming to have been trained by Syrian intelligence agents in Syria.
Syrian President Bashar al-Assad called Iraq's accusations "immoral" and demanded Baghdad provide proof to back them up.
Maliki on Monday accused Syria of not cooperating with Iraq's investigations despite being given names, addresses, documents and detailed evidence.
"The crisis with Syria is not new. We have made contacts with ... Syrian officials regarding the activity of leaders from the disbanded Baath Party and terrorist organizations that work against Iraq from Syrian lands," he said on Thursday.
Iraqi and U.S. officials have long accused neighbors Syria and Iran of backing Sunni and Shi'ite militants, respectively. Both countries have tetchy relations with Washington.
U.S. forces pulled out of Iraqi cities in June, under a security agreement that requires them to withdraw by 2012, and have played a more low key role in the country since then.
"Some neighboring countries consider the MNF (U.S. troop) presence damaging to their national security and ... interfere under the pretext of resisting occupation," Maliki said. "After the withdrawal of U.S. troops, this is no longer acceptable."
Iraq says it is appealing to the U.N. Security Council for assistance in setting up an international tribunal to prosecute crimes instigated in Iraq or assisted by other countries.
Syria and Iraq, for long ruled by rival wings of the Baath party, were at odds for years after Saddam came to power in 1979, but ties improved, as did trade, in the late 1990s. Tensions resurfaced after the 2003 invasion of Iraq.