A GIANT Chinese submarine has been spotted in new satellite pictures – sparking concern over its secretive purpose.

The suspected drone sub, which could be the largest in the world, has been spotted at the Guangzhou Shipyard in southern China by satellites.

According to Naval News, the vessel was in a floating dock in the shipyard where China has been rapidly building invasion barges.

Renowned naval expert HI Sutton said it measures around 148ft in length and 15ft in width.

The design of the new submarine has not previously been reported.

It appears to have no sail and large X-form rudders giving it a modern appearance.

Compared to other Chinese subs like the Type-041 with a nuclear battery that was launched in a shipyard near Wuhan, the new submarine is smaller and is not thought to have a nuclear element.

It also differs from China’s ‘Olympic’ submarine that emerged in early 2022.

The new submarine is thought to be based on a prototype of the world’s first sailless submarine launched at the Jiangnan Shipyard in Shanghai in 2019.

While that sub appeared to be experimental with no torpedo tubes or sonar, it is possible that the new sailless sub is a remake of the prototype.

Unlike the west, China has a history for secretly designing military equipment and hiding its capabilities as well as its use until the products appear fully formed.

Being smaller than usual diesel-electric submarines, this new boat is possibly more suited to shallow water operations.

But, it is thought to have torpedo tubes and potentially a towed sonar array meaning it could attack ships or other submarines.

HI Sutton praised the subs “distinctive ultra-modern layout” and admitted it was a surprise to analysts to see the secret vessel.

Reports also suggest that it could be designed for missions carried out by special forces or for battles on the seabed.

According to Naval News, the submarine appears to be an uncrewed vessel which is increasingly common in China.

The country has the world’s largest program dedicated to constructing extra-large uncrewed submarines.

It already has at least five crewless vessels in the water but if the new submarine is a extra-large uncrewed underwater vehicle (XLUUV) then it is the largest in the world, Naval News reports.

If this is the case, it is around six to eight times larger that the US Navy’s Orca XLUUV.

But, if the submarine really is uncrewed, it is not clear why it would have to be so large.

HI Sutton says one explanation could see it be used to attack ships or submarines.

An alternative reason may be that it is designed for special forces missions or even seabed warfare. 

The revelation of the new secret submarine comes after a major blunder where one of China’s most sophisticated nuclear-powered submarines sunk.

Chinese authorities were left in a panic as they tried to cover up the setback to one of their priority weapons programs for months.

The sunken sub was first uncovered by US officials through satellites.

It comes as China continues to expand their navy fleet – especially the nuclear submarines, reports the Wall Street Journal.

The country claims to be building a world-class military in order to deter away aggression and safeguard its own overseas interests.