Saudi ISIS
The Saudi crown prince's son participated in the strikes against Islamic State Twitter/@RajaChemayel

Saudi pilots who carried out air strikes against Isis (now known as the Islamic State) have started to receive online death threats from supporters of the terror group after their photos were published.

Saudi Press Agency (SPA) released pictures of eight pilots who it said were involved in the US-led coalition operation in Syria, one of which included the son of Crown Prince Salman bin Abdul Aziz.

One social media user tweeted the hashtag #LetTheHuntBegin while another called the pilots "apostates".

Other users commented that the pilots were "wanted by IS" and another warned that their throats "will sooner or later be slit".

"The Saudi pilots returned safe and sound on Tuesday morning after having accomplished their duty in carrying out successful and effective strikes against the Islamic State extremist organisation in Syria," SPA said.

"My sons, the pilots, fulfilled their obligation towards their religion, their homeland and their king," SPA quoted the crown prince as saying.

The crown prince added he was "proud of the professionalism and bravery" of the Saudi pilots.

The strikes in Syria by the US-led coalition have killed at least 70 IS militants, 50 al-Qaida-linked fighters and eight civilians, according to activists.

The United States has conducted over 200 air strikes on the group's positions in Iraq since August, while Saudi Arabia, the United Arab Emirates, Jordan, Bahrain and Qatar have joined or supported the strikes in Syria.

The terror group views the monarchy present in Saudi Arabia as illegal and the Saudi elite see the group as a growing security threat to their vast oil wealth.

The kingdom's grand mufti, Abdul Aziz al-Sheikh, said jihadist groups in the Middle East "have nothing to do with Islam and [their supporters] are the enemy number one of Islam".

However, the country has been accused of financing extremist groups and aiding the spread of the extremist Salafist ideology upon which the terror group is built.