Samsung has released a teaser image for the Galaxy S4 smartphone, at the same time that the phone has been 'revealed' in a new video posted on the internet in China, Digital Spy revealed.

Posting the teaser picture on Twitter, the South Korean firm said: "The countdown for #TheNextBigThing has begun. Who's ready for the Global Unpacked Event on March 14?"

The tweet was referring to a planned launch event in New York on Thursday (March 14), at which the Galaxy S4 is expected to be revealed.

The teaser image appears to be of a phone that bears many similarities in design language to the Galaxy S3, Samsung's current flagship phone.

But after images supposedly of the new Android-powered S4 emerged on Chinese forum 52 Samsung, a video of the phone has now surfaced online.

As with the leaked images, the video shows a handset that takes its lead form the design of the Galaxy S3, but in a slightly taller and more rectangular body.

It appears to be fitted with a 5-inch display but with a thinner bezel than a Galaxy S3. The phone is shown running Android 4.2.1, but with Samsung's own TouchWiz user interface over the top.

The revealed S4, on the China Unicorn network, appears to have dual SIM card slots, a feature popular in Asian markets.

The design language of the phone matches up with the leak yesterday, but it remains unclear whether this is actually the S4 or another dual SIM Samsung phone.