The MKs, members of the National Democratic Assembly, coordinated their visit with Lebanese Parliamentary Speaker Nabih Berri.
The party's MKs, Azmi Bishara, Jamal Zahalka and Wasil Taha, denied reports that they will meet Hizbullah members.
Attorney-General Menachem Mazuz ordered the police to interrogate the MKs about their visits to Syria and Lebanon upon their return to Israel.
Mazuz's deputy, Attorney Raz Nezri, dispatched a letter to the police intelligence unit demanding the MKs be questioned over illegal visits to enemy states.
'Willing to pay the price'
Under Israeli law, Israeli nationals are forbidden from visiting enemy states, and offenders could face sentences of up to four years in jail.
Nezri noted that Israeli national could visit enemy states without committing an offense only with a special permit signed by the prime minister or the minister of the interior.
Bishara warned Baath party officials that Israel could launch a multi-front war against its neighbors to reinstate its military deterrence which was scathed in the war with Hizbullah.
Bishara told the London-based Arabic-language daily that for Israeli Arabs solidarity with the Arab world has its price and his willing to pay that price, referring to the possibility of being prosecuted in Israel for visiting enemy Arab states.