They describe the tower as being located in the grade A office section of Taikoo Place which accommodates 300 multinational companies.

A Swire Properties spokeswoman said Cheung Kong had not asked for permission before releasing the pamphlet. 'Taikoo Place is wholly developed, owned and managed by Swire Properties. Any party who wants to use our office images for commercial purposes should get our consent in advance,' she said.

An industry source said Swire had sent a letter to Cheung Kong through its lawyer, stating that Taikoo Place was a Swire Properties trademark.

Cheung Kong has now changed the content of its pamphlets, with some describing the tower as 'an exalted residence at Island East' but with a footnote saying it is located at 'Taikoo Place MTR exit'. The posters and pamphlets still include images of the office blocks.

A Cheung Kong spokeswoman said the company did not need permission to use the term 'Taikoo Place' in its material since it was only used as a geographical reference.

'The reference to Taikoo Place was purely directional to provide readers with an accurate understanding of the location of our Casa 880 development, in accordance with the commonly used MTR signposting,' she said.

'Since the reference was for directional purposes only, we do not think that it was necessary to obtain approval from any party or authorities.'

While the Estate Agents Authority said it kept a check on the accuracy of promotional material, its mandate was restricted to agents.

Eric Cheung Tat-ming, an assistant professor at the University of Hong Kong's law faculty, said using Taikoo Place in advertising material might confuse consumers and imply that Swire was developing the tower.

He said Cheung Kong might be guilty under civil law of the offence of 'passing off'.

'This legal concept is about when a product or an invention is always associated with a certain company. If it were Causeway Bay or Quarry Bay, there shouldn't be any problem. No one can monopolise Causeway Bay or Quarry Bay.'