Lebanon's militant Hezbollah group says one of its top commanders has been killed while fighting Islamic State militants in Syria.

The 44-year-old Ali Al-Hadi Al-Ashiq is the latest fatality for the Shiite group that has fought alongside Syrian government forces in the civil war next door since 2012.

Hezbollah said on Wednesday that he was killed fighting IS in the central desert of Palmyra on Monday.

Hezbollah sent thousands of fighters to Syria, helping government forces in major battlefields victories against armed opposition and Islamic militants.

More than 1,000 Hezbollah fighters have been killed there.

Al-Ashiq, also known by his nickname Alhaj Abbas, was among first Hezbollah commanders sent to Syria and he took part in the key battle in al-Qusair, near the Lebanese border.

He also fought against Israel.