Lok said the authority was jumping the gun by pouring millions of dollars into producing 21 videos that all supported the expansion plan. He estimated the production cost of the videos would 'be in the millions' because 'videos take ages to create, even just one minute'.

'[But] you are dealing with airports so this amount of money is peanuts,' he said.

'I'm not surprised ... but it's premature,' he said of the videos which feature high-profile personalities such as Cathay Pacific chief executive John Slosar, transport sector lawmaker Miriam Lau Kin-yee, Ocean Park chairman Allan Zeman, Hollywood director John Woo Yu-sen and actor and Canto-pop singer Aarif Rahman.

The videos echo the sentiment in the authority's written documents which state that Hong Kong's overall competitiveness as a world city would be at risk if the third runway plan does not go ahead.

An authority spokeswoman refused to disclose the amount spent on the videos or reveal the name of the company that won a tender for the project. She also refused to reveal the total budget of the marketing strategy for the authority's 2030 master plan which includes roving exhibitions, public forums and advertisements on TV and billboards.

She did confirm that all the interviewees appeared 'on a voluntary basis at no cost to us'.

The videos are currently screening on more than 100 monitors throughout the airport.

The authority has not spent any money on producing equivalent videos featuring local personalities who do not want the third runway.

One video production company in North Point provided a conservative quote for a half-day of filming for one video at HK$12,000, so 21 videos would total about HK$250,000.

Lok, who supports a third runway, but not at the existing site, said he was not surprised that the videos only presented one side of the argument and he criticised the authority for hiding vital information about the feasibility of the third runway plan.

'If you look at the technical report, there is a caveat laid down that this scheme requires very extensive revision with Pearl River Delta airspace which we share with several other airports,' he said.

'To develop and implement the changes, we need to confer with Macau and mainland authorities.

'If you fail to get their consensus, there's no point talking about how much it's going to cost or if it's cost-effective. They have never mentioned this caveat in all the publicity, which I think is rather immoral.'

In documents for the master plan, the authority states its intention to ensure a 'transparent, professional and objective planning process'.

Questions the Post sent to the authority on the spending several times last week went unanswered and at a public forum on the master plan yesterday, Howard Eng Kiu-chor, executive director of airport operations, did not take questions from the media.

$136b

The Airport Authority's estimate of the cost, in HK dollars, of a third runway at Chek Lap Kok. A three-month consultation runs to September 2