They also say the flag featuring the Star of David was unofficial and was sometimes displayed on Jewish-owned ships in the region.

The claim appears across social media, examples here, here, here, here, here, here, here and here.

“This is the original Palestine flag from 1939,” this post (archived here) reads. “Palestine was then only a region controlled by the British mandate. This flag was the inspiration for the current Israeli flag from the declaration of the state of Israel in 1948.

“The argument Israel occupying this land and state is one more lie from Paliwood.”

Many of the posts (example here) refer to and provide images of the 1939 Larousse Illustrated Encyclopedic Dictionary and its flag appendix page.

Larousse is a French publishing house known for its reference books.

The featured flag is blue and white with a golden Star of David in the centre.

But this was never the flag of Palestine.

Associate Professor Shai Ginsburg, an Asian and Middle Eastern Studies expert at Duke University, says as Palestine was under British mandate in 1939, its official flag was the Union Jack. 

“The British Mandatory authorities did not use the Star of David on any of their flags,” Dr Ginsburg said. 

“The Star of David was identified with the Zionist movement and was used mainly by the different arms of the movement and its supporters, though non-Zionist Jews also used it.”

Rashid Khalidi, professor of Modern Arab Studies at Columbia University, told AAP FactCheck the post is “complete nonsense”. 

He pointed to a flag of the time featured on the UK’s Imperial War Museum website.

Another flag used during the mandate period was a red flag featuring a Union Jack and a white circle with the word “Palestine” written inside it.

This was the British civil ensign flag and was reportedly used for Palestinian merchant ships. 

Shay Hazkani, an associate professor at the Joseph and Rebecca Meyerhoff Program and Center for Jewish Studies at the University of Maryland, told Reuters that the flag in the Larousse book was unofficial and would sometimes appear on Jewish-owned ships during the mandatory period.

The contemporary flag of the State of Palestine features pan-Arab colours and resembles the World War I-era Flag of Hejaz, which was used during the Arab Revolt against the Ottoman Empire.

The flag of Israel is based on the "flag of Judah" designed by American Zionists in 1891. It features blue and white stripes along with the Star of David. It was displayed when Israel proclaimed independence in 1948 and later adopted as the country's official flag.

The claim about the 1939 Palestine flag has also been debunked here and here.