Victorian authorities say they will remove painted artwork from security bollards in Melbourne's CBD after a graffiti artist says he was stopped by police while working on one of the concrete blocks.

The artist, one half of graffiti art duo Cit Cat, said he was stopped by police just after midnight on Saturday while he was adding to a bollard he painted on Thursday outside the GPO building on the corner of Bourke and Elizabeth streets.

He said he was putting a paper paste-on on his Cat Woman artwork when he was stopped by five police.

"They demanded I give my real name, I didn't want to do that and they threatened to arrest me," he said.

"They asked me why am I doing this. I explained that I just wanted it to be a positive expression and share it with people.

"It was overall quite humiliating … I felt shaken up."

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The artist said police told him to expect a summons in the mail for a graffiti misdemeanour.

A police spokesman said they would treat the artists painting bollards on a case-by-case basis.

About 200 bollards have been placed around the city to protect pedestrians from vehicle-based attacks

Earlier this year, six people were killed and dozens injured when a car was driven into pedestrians during the busy lunchtime period in Bourke Street.

After the bollards were installed, artists painted the concrete cubes and covered them with colourful materials in what has been dubbed "boll-art".

The City of Melbourne said on Tuesday it did not encourage people to paint the bollards as they were not owned by the council, but instead rented.

The council had tweeted earlier in the week it would not be removing art from the bollards.

It later clarified it was referring to the material coverings.

"If any of the bollards are painted, we will be able to remove the paint without incurring significant costs," a spokeswoman said.

It is unclear if the council will paint over the bollards immediately, or when they are eventually removed to make way for more permanent protective structures such as seating and planter boxes.

Cit Cat have painted several security bollards around the city, including in Southbank. ( ABC News: Iskhandar Razak )

The bollards have been put in place as part of a $10 million State Government move to beef up security in the CBD.

Today Premier Daniel Andrews said the artwork was "great".

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"You would expect nothing less in the cultural capital of our nation," he said.

In a tweet, Lord Mayor Robert Doyle also indicated his support for the spontaneous show of creativity.

The Cit Cat artist said it was confusing for artists as the idea had been promoted as an expression of artist culture.

"The council already tweeted they think it's not an offence and they are pretty much promoting that it's a good idea. It's not affecting anyone and they're not going to be removing any art," he said.

"It's all mixed messages.

"I really wanted people to think about love, not to think about why they're [the bollards are] there."