A Dutch architectural firm has apologised for its design of twin skyscrapers in central Seoul which resemble the exploding World Trade Center towers in New York and have infuriated families of the victims of the September 11 attacks.

The blueprint for the luxury apartment buildings was released last week and shows a structure which juts out at the middle to accommodate pools, restaurants, cafes and a gym.

Relatives of victims of al Qaeda's September 11, 2001, attacks on the United States have expressed outrage, according to U.S. media reports, saying the designers have no respect for those that died and branding the design a cheap publicity stunt.

Designer MVRDV said it had not intended to create an image resembling the attacks, and it did not see the resemblance during the design process.

"We sincerely apologise to anyone whose feelings we have hurt. It was not our intention," the company said on its website.

It did not indicate whether it would change the design.

"A real media storm has started and we receive threatening emails and calls of angry people calling us al Qaeda lovers or worse," it said on its Facebook page.

The district developer is expected to decide on the final design plans by March.