Millions of museum visitors in the US capital will no longer be able to take pictures of themselves in front of a T-Rex dinosaur using a camera mounted on a rod.

The Smithsonian Institution in Washington DC has banned the use of so-called selfie sticks in its complex of museums, the world's biggest, citing the need to protect visitors and museum objects, especially in crowded conditions.

“We encourage museum visitors to take selfies and share their experiences – and leave the selfie sticks in their bags,” the Smithsonian said in a statement.

I don’t think you could have predicted there would be such a thing

The move follows similar restrictions on the tourist item at other destinations, including New York's Metropolitan Museum of Art.

It is the first change in years to the Smithsonian's rules, amid the sudden spike in popularity of visitors wanting to capture better composed snapshots of themselves using the sticks.

“I can't think of any recent change that's been similar to this,” spokesman John Gibbons said. “I don't think 10 years ago that you could have predicted there would even be such a thing, let alone that it would be so popular.”

Gibbons said the rule change was not inspired by any particular incident, but was meant to be preventative.

The institution already prohibits people from bringing tripods, monopods and large backpacks in its complex, which groups 19 museums and galleries, the National Zoological Park and nine research centres. It had more than 28 million visits last year.