Art gallery attendants are usually occupied by ensuring that a respectful silence is maintained and that no one strays too close to priceless masterpieces.

But from Saturday, staff at the Tate Modern’s new exhibition inviting visitors to sketch on the gallery’s floor will be tasked with monitoring the drawings in case some who take part are tempted to daub the kind of rude graffiti normally seen on the back of lavatory doors.

People of all ages will be welcome to doodle on the floor of the London art gallery’s 500ft-long Turbine Hall for a project called Mega Please Draw Freely, devised by Japanese artist Ei Arakawa.

The gallery, however, has admitted it is a little nervous about what some might draw.

While participants will be able to “draw freely” whatever comes into their heads in the spirit of free expression, gallery staff will be on standby to swiftly cover up puerile, or even offensive, additions to the art project for the benefit of other visitors.

The Tate advised that “the space will be monitored” by its Family Team, which will also control the flow of people in and out of the Turbine Hall.

If they spot “any offensive content that could negatively affect our young audiences’’, these additions to the gallery floor will be “drawn over where possible”.

Be it silhouettes or sketches, visitors are encouraged to let their imagination run wild

Credit: Paul Quezada-Neiman/Alamy Live News

The principle behind the Please Draw Freely project is to allow visitors to express their own creativity, and it is understood there are no pre-set rules dictating what is allowed to be drawn or written on the floor.

The same principle applies to a series of banners which the public can also draw on at the Tate, and which will be successively hung up in the gallery each Monday of the six-week installation.

In tackling scribblings or imagery that could be offensive, the Tate will not be clamping down on political statements marked on floor or banners, and will encourage the public to express their views.

It is understood that this will be within reason, and offensive political images such as swastikas will be banned to ensure the project remains fully inclusive.

A spokesman for the gallery said: “Tate’s aim is to create a space for artists and their work, offering a place for public debate where freedom of expression is encouraged.

“With our young audiences in mind, we want to ensure the spirit of the project is both positive and inclusive.”

Mega Please Draw Freely is inspired by a previous project, Please Draw Freely, devised by late artist Jiro Yoshihara in 1956 to undermine a perceived conformism of the post-war Japanese mindset.

Now, the project has been mirrored on a grander scale in the 35,520sq ft Turbine Hall.

The Turbine Hall’s concrete floor has been coated with a protective material which will prevent the drawings becoming permanent

Credit: Yui Mok/PA

Mr Arakawa, who often works as a performance artist, told The Telegraph: “Gutai [the movement which inspired the original Please Draw Freely] was inspired by how children think and act playfully.

“Their art, especially early on, had the power to break the frame of what museum, painting – and art – should be.

“I want many participants to interact with the architecture of Tate Modern’s Turbine Hall by drawing on the floor, and to discover some surprising ideas hidden in themselves. I want us to be outside the box.”

The polished concrete floor of the former power station has been coated with a protective material which will prevent the public’s contributions becoming permanent.

When the project ends after a six-week run beginning on Saturday, the protective flooring will be removed and recycled.

It will be entirely free to take part in the project, and coloured crayons will be provided on site for visitors to join in.