Sharon: Found indirectly responsible for massacres in Israel
Mr Sharon has hired a Belgian defence lawyer, on the advice of attorney-general Elyakim Rubinstein, in case the trial goes ahead, the radio reported.
Mr Sharon was Israeli Defence Minister at the time and his role in the massacre was criticised by an official Israeli panel set up after the events.
The 73-year-old leader says the case is a veiled attack against all Israelis and Jews.
"It's not a personal question - by attacking me personally they are looking to attack Israel and the Jewish people, but we will stop it," Mr Sharon told reporters on Thursday.
A Belgian judge is currently investigating the claim. Under Belgian law, persons may be charged with war crimes or crimes against humanity regardless of the nationality of the victims or the accused.
A spokesman for Mr Sharon refused to comment on the Army Radio report.
A statement from his office said: "Any decisions taken about the ongoing events in Belgium will be made by the Israeli judiciary in consultation with other experts."
BBC analyst Roger Hardy says that Mr Sharon had originally ignored the possibility that he might be summoned to appear before a Belgian court, but Israeli officials now fear that cases being brought in Europe may have opened a Pandora's box of litigation.
Army Radio said Israel has been told that cases are also being prepared against current Chief of Staff Shaul Mofaz and air force commander Major General Dan Halutz for alleged human rights violations following recent military actions against Palestinians.
Legal threat to officials
The foreign ministry has meanwhile begun examining where else in Europe Israeli officials might face being arrested on charges of human rights abuses during their travels abroad.
A foreign ministry source quoted by Ha'aretz daily said "there may be problems in the future and those who are famous may be at risk".
Mr Sharon cancelled a planned visit to Belgium during a trip to Europe earlier in July for what his office called "calendar reasons".
However, a Belgian senator visiting Lebanon said on Wednesday that the Israeli leader did not go because of the risk of prosecution.
Denmark, on the other hand, says it will not carry out a threat to arrest Israel's ambassador-designate to the country on suspicion of human rights abuse.
Danish media reported Justice Minister Frank Jensen said on Wednesday Carmi Gillon, the former chief of Israel's internal security service, Shin Bet, could face immediate arrest when he takes up his post next month.
Mr Jensen said Mr Gillon could be prosecuted under the terms of a UN anti-torture convention after he admitted using "moderate physical pressure" on Palestinians arrested during the current conflict.
Israeli Foreign Minister Shimon Peres told Israel Army Radio he had no intention of replacing Mr Gillon, adding: "If Denmark acts according to this method it cannot allow in any member of the PLO who at one time was involved in terrorism."