London: Hollywood actor Leonardo DiCaprio has written a letter to officials in California urging them to ban the sale of shark fins in the state.

The 36-year-old star has put his weight behind the proposed Assembly Bill 376, which would make it illegal to possess, sell or trade shark fins, a website reported.

"The International Union for the Conservation of Nature has concluded that a third of shark species are now threatened with extinction of some kind. And recent estimates state that up to 73 million sharks are killed each year for use in shark fin soup and other products," DiCaprio wrote in a letter to members of the California State Senate.

"Traditionally shark fin was affordable only to the elite, and consequently the issue of decimation of species was not a concern. But with the explosion of the world's population and an increasing number of wealthy consumers, this can no longer be considered true, as has been evidenced by the decimation of shark populations worldwide," the letter read.

Hollywood stars Edward Norton, Kristen Bell, Paul Rudd Scarlett Johansson and pop star Kesha have also backed the Bill to save sharks.