Iraq says it has reached an agreement with Syria to seal their long desert border and stop the infiltration of foreign insurgents.
Saleh said Iraq wanted balanced relations with its neighbours
Iraqi Deputy Prime Minister Barham Saleh announced the move after talks in Damascus with President Bashar Assad.
He said the Syrian leader had assured him that Damascus would try to prevent any kind of infiltration.
Mr Saleh added that the border would be controlled from both sides, with the use of special security forces.
"We have agreed that specialised security forces would
co-operate to investigate the issue of the infiltration of
terrorists to launch military operations, and to prevent
all aspects of infiltration," he told reporters.
His visit to the Syrian capital was the first by a senior Iraqi official since the US-led coalition transferred power to the new interim government in Baghdad.
The BBC's Peter Greste, reporting from Baghdad, says the agreement is a breakthrough, and a tacit acknowledgement by the Syrians that foreign fighters have crossed their frontier into Iraq.
But he says sealing the 600km (370-mile) border will not be easy, as it is a largely artificial line in the sand, and local tribesmen and smugglers have wandered across it for generations.
The United States imposed sanctions against Syria earlier this year, accusing Damascus of not doing enough to stop the movement of militants from its territory into Iraq.
Our correspondent says President Assad will be hoping this new agreement will ease criticism from the US, as well as from the interim administration in Iraq itself.
Offer of troops
Mr Saleh was in Syria to pave the way for a forthcoming visit by Iraqi interim Prime Minister Iyad Allawi, who will also visit Jordan and Iran.
Mr Allawi is expected to decline the offer of troops from other Arab countries to join a purported multinational peacekeeping force in Iraq.
"The Iraqi stand toward this issue is clear," Mr Saleh said.
"Iraq is looking forward for stable and balanced relations
with neighbouring countries, but military intervention from
any neighbouring country could be a complicating factor."
UN envoy Lakhdar Brahimi also met the Syrian president on Sunday.
He said both he and Mr Saleh were "encouraged" by their discussions with Mr Assad, and by the contribution Iraq's neighbours were making to peace and security in Iraq.
"Those who opposed occupation will see that now is the
time to consolidate (Iraq's) sovereignty and
independence," he said.
The agreement came as the Iraqi Foreign Minister, Hoshyar Zebari, prepared to head for Brussels for a series of meetings with Nato and the European Union.
He said he would seek assistance from Nato to implement tougher border controls, and would ask the EU - collectively and as individual nations - to provide economic assistance direct to the Iraqi people, rather than through intermediaries.
He told the BBC's World Today programme that priorities included help to build institutions, including ministries, and assistance on training and technical matters.