Lebanese Shiite gunmen who kidnapped more than 20 people said on Thursday they would kill a Turkish hostage first if their kinsman captured by rebels in Syria was hurt and said they were looking to seize more Turkish citizens.

The Meqdad family says it is seeking to put pressure on the Free Syrian Army (FSA) to release Hassan al-Meqdad by targeting both Syrians it says are part of the rebel force and citizens of Turkey, one of the rebels' regional sponsors. The family is holding one Turk and the rest of its captives are Syrians.

The kidnapping has evoked memories of Lebanon's own civil war, reinforcing fears that the Syria conflict could trigger more instability in a much smaller neighbour where Damascus has had a major influence over politics and security for decades.

A member of the Meqdad family was quoted on Wednesday as saying citizens of Qatar and Saudi Arabia were also on their list of potential targets. In response, Gulf states ordered their citizens to leave Lebanon.

But Maher al-Meqdad, the spokesman for the family, said the Meqdads were only targeting the FSA and Turks, adding that the number of Turkish captives "was likely to rise".

"If Hassan (al-Meqdad) is killed, the first hostage we will kill is the Turk," Maher al-Meqdad told Reuters.

"Regarding Saudis, Qataris and Gulf nationals, they are not targets for the Meqdad family," said Maher al-Meqdad, speaking in an area of southern Beirut controlled by Hezbollah, the Iran-backed, Shiite Lebanese party and guerrilla group.

The family says Hezbollah, a party closely allied to Syrian President Bashar al-Assad, has nothing to do with the kidnappings.

The Turkish hostage was interviewed after his abduction on Wednesday by a Lebanese television channel. He said he had come to Lebanon for a business trip.

The Turkish Foreign Ministry said it was in contact with the family of the kidnapped Turk, who it named as Aydin Tufan Tekin.

"Our ministry and Beirut Embassy are continuing intensive efforts to secure the release unharmed of our kidnapped citizen," it said in a statement released late on Wednesday

Meqdad said Lebanese Foreign Minister Adnan Mansour had been in touch to seek the release of the Turk, but added that he would not be released until Hassan al-Meqdad was freed.

"Our adversary is only the Free Syrian Army," he said. "We want our relative."