Diners have described being given 15 minutes to finish their meals and evacuate a major Melbourne pier last night, after engineers found it was unsafe for use, prompting its immediate closure.

Key points: The pier will remain closed for at least one month after engineers found its stability had deteriorated rapidly

The pier will remain closed for at least one month after engineers found its stability had deteriorated rapidly A number of venues, including restaurants, a pub and cocktail bar operate from the pier

A number of venues, including restaurants, a pub and cocktail bar operate from the pier The main business operator on the pier has disputed findings that the pier is dangerously unstable

Development Victoria said it received advice from an engineering firm about midday on Wednesday that despite all efforts to stabilise Dockland's Central Pier, there had been rapid deterioration in the structure.

The century-old Central Pier is home to several businesses including a pub, cocktail bar, restaurants and event venues.

Development Victoria chief executive Angela Skandarajah said the engineers had reported that an issue with the footings of the pier had compromised its stability.

"It was deteriorating faster than they had anticipated," she said.

"They haven't collapsed as yet but there's a potential issue there."

Restaurants, a pub and cocktail bar are among the businesses that operate from the pier. ( ABC News: James Hancock )

The pier has been assessed for its stability every two months since November 2018 and was previously found to be safe for use.

Protective barriers were erected on Wednesday night to prevent entry and Ms Skandarajah said the pier would remain closed for at least a month.

She said engineers would visit the pier on Thursday to conduct more assessments and provide a more detailed report.

'You had to wolf down your dinner'

Diners said they were told to leave shortly before 7:00pm on Wednesday.

"We placed our orders and the entrees came out and then all of a sudden the guy says we have to evacuate, you've got 15 minutes," one diner told the ABC.

"So they're madly cooking up everything to put it on the table and we just finished and we paid our bill and then we came out.

"All they said was it was a structural issue with the pier."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 59 seconds 59 s Diners describe the evacuation of Docklands restaurant after pier deemed 'unsafe'

"You had to wolf down your dinner in 15 minutes … you saw the fear in the restaurateur's eyes," one of his dining companions said.

A woman from the same dining group said she questioned the logic of the 15-minute timeframe.

"Fifteen minutes until what? What evidence do you have to support the fact that we have 15 minutes?"

Deakin University's Commerce ball was to be held at a venue on the pier on Wednesday night but was moved to another location.

'I think this is it for the pier'

Jeff Gordon owns and operates the Lady Cutler showboat cruise out of Central Pier and said he was notified of the closure this morning.

"We're in a very difficult situation at the moment," he said.

Mr Gordon said he had cruises booked for more than 200 people this weekend but now had nowhere to dock, or to load passengers and provisions.

He said the decision has thrown dozens of bookings into chaos, well into next year, for many other boats that use the pier.

Development Victoria's assessment of the pier as unstable has been questioned by one of the pier's venues. ( ABC News )

"We're all struggling with this," he said.

"We're all being relocated, and there's not a lot of room left on Victoria Harbour, most of it has been taken up with people's private yachts, so the commercial boats have really been squeezed out now and this is the icing on the cake."

He is not waiting for the pier to reopen.

"If it's a full evacuation of the pier, there must be something serious, and that will take quite a lot of work because they'll have to open up the floors of the buildings to get to the piles underneath and drive new piles underneath.

"I really think the month thing is a bit of a fortune-telling thing, I don't think that's going to happen. I think this is it for the pier."

'Too early' to know if pier can be saved

Ms Skandarajah said it was "too early" to answer questions about whether or not the pier would be able to reopen in the future.

"I can't comment on that yet. Let's wait for the advice to inform whatever decisions need to be made," she said.

She said she was "not in a position" to comment on whether businesses affected by the closure of at least one month would be offered compensation.

The chief executive of Atlantic Group, which runs several venues on the pier, said he was considering legal action over the month-long closure.

Hatem Saleh said his company disputed the findings of the engineers reporting to Development Victoria.

"I would probably suggest that if that engineer was working for us, he wouldn't be working for us," Mr Saleh told ABC Radio Melbourne.

"We've had our own engineer working underneath the pier for many, many months and we don't have the same understanding as what has been told to us."