He would have the talks outside Syria if the authorities released tens of thousands of detainees.
Syrian officials said this week that political opposition figures could return to Damascus for "national dialogue" and that any charges against them would be dropped.
That followed a speech Assad gave three weeks ago in which he called for reconciliation talks, although he said there would be no dialogue with opponents he called "terrorists".
Assad has been trying to crush an uprising that began in March 2011 with mainly peaceful political protests but that has escalated into a civil war resulting in 60 000 deaths.
His comments were dismissed by most opposition figures, who insist on his departure as a precondition for talks, but Alkhatib appeared to soften that position slightly.
"I am prepared to sit down directly with representatives of the Syrian regime in Cairo, Tunis or Istanbul," Alkhatib said on his Facebook page on Wednesday.
He set out two conditions of his own: the release of 160 000 detainees held in Syrian prisons and intelligence facilities, and instructions to Syrian embassies to issue new passports to Syrians whose documents had expired.
Underlining the continued rifts among Assad's foes, the opposition Syrian National Council immediately distanced itself from his comments.
"The Syrian people are paying a high price to obtain their right to full freedom … The Syrian National Council affirms its absolute commitment to the Syrian people's will and rejects any settlement with the Syrian regime or negotiation with it."
In early January, Assad announced plans for a reconciliation conference with opposition figures "who have not betrayed Syria", though he said there must first be an end to regional funding and arming of rebels fighting to overthrow him.
"Should we speak to gangs recruited abroad that follow the orders of foreigners? Should we have official dialogue with a puppet made by the West, which has scripted its lines?" he said.
Denouncing "unrelenting horrors" in Syria, United Nations secretary general Ban Ki-moon appealed on Wednesday for an end to the violence and for more aid to address a situation he said was catastrophic and worsening by the day.
"How many more people will be killed if the current situation continues?" he asked, addressing a donors conference in Kuwait aimed at raising money for UN humanitarian work. "I appeal to all sides and particularly the Syrian government to stop the killing … in the name of humanity, stop the killing."
Syrian activists said more than 100 people were found shot dead with their hands bound in the embattled northern city of Aleppo on Tuesday, the latest reported massacre during the course of the conflict. – Reuters