Israeli President Moshe Katsav has invited his Syrian counterpart, Bashar al-Assad, to visit Jerusalem for talks on a peace accord for the Middle East.
Assad has said he is ready to resume negotiations with Israel
Mr Katsav, Israel's ceremonial leader, told public radio he invited Mr Assad "to seriously negotiate" with Israel.
Last month, Mr Assad said in newspaper interviews that he was ready to resume negotiations with Israel.
But responding to Mr Katsav's remarks, Syria said they were not a serious answer to its calls for peace talks.
"We need a serious response... A serious response is to say yes, we are interested in peace, we
want to negotiate," Syrian Expatriates Minister Buthaina
Shaaban told CNN.
Israeli Prime Minister Ariel Sharon said on Sunday that talks could only begin if Syria "stops backing terrorism".
The BBC's Paul Wood in Jerusalem says the issue of talks is dividing the Israeli political establishment.
A number of Israeli ministers have urged the government to respond to such overtures for peace.
Mr Sharon told his cabinet on Sunday there was no need to re-start talks with Syria until reports that it wanted a dialogue were clarified.
Israel's president told Israeli radio on Monday: "I invite President Assad to come to Jerusalem to seriously negotiate with Israeli leaders on the conditions of a peace accord".
Mr Katsav added that there were no preconditions to his invitation.
"We have our doubts, a lot of doubts, concerning the Syrian president's intentions and motives," he added.
"His motives for launching this initiative were not pure, but I think his proposal should nevertheless seriously and thoroughly be examined."
There was no comment on the invitation from Ariel Sharon's office, or any immediate reaction from Syria.
Israel and Syria are still technically at war: peace talks broke down four years ago over the future of the Golan Heights which were captured from Syria in the 1967 war.
Syria has recently urged the United States to help revive the talks, which at the time were leading Israel to agree to partially return the Golan Heights to Syria.
Mr Sharon said on Sunday he believed Syria was still helping agents of the Lebanese group, Hezbollah, which is accused of involvement in attacks on Israel.
It came as Israeli media gave heavy coverage to allegations that a humanitarian relief flight sent by Damascus to the Iranian earthquake returned laden with weapons for Hezbollah.
Mr Sharon said when support for such groups stopped, Israel would be ready for negotiations.
"Israel is ready and willing to negotiate once Syria stops its help to terror," he said.
Other conditions include:
- Syrian help for returning missing Israeli soldiers
- Return of the remains of the Israeli spy Eli Cohen for burial
Two leading Israeli cabinet ministers - Finance Minister Binyamin Netanyahu and Foreign Minister Silvan Shalom - have already spoken in favour of resuming talks with Syria.
Mr Netanyahu suggested that Syria is weak now and could be pressured into peace without Israel having to give up all of the Golan Heights.
Israeli Defence Minister Shaul Mofaz believes Syria's apparent new position is the result of US pressure.
The BBC's Paul Wood says the chief sceptic is Ariel Sharon and no talks will happen without his say so.