The first official plans for redeveloping the site where the World Trade Center stood have been made public by authorities in New York.

Six alternative proposals were unveiled, each of which include a memorial to the victims of the 11 September attacks.

It's the same as Gettysburg or Pearl Harbour

Joseph Maurer, victim's father

The plans are rough drafts and will be narrowed down to one final design by December.

About 5,000 people will be given an opportunity to comment on the plans at a public meeting on Saturday.

The debate about what should replace the Twin Towers has been highly charged, with many victims' relatives demanding that an area be left untouched out of respect to the nearly 3,000 people who died.

The publication of the plans comes a day after forensic teams officially ended searching through debris from the site for human remains.

Place of remembrance

The six concepts were commissioned by the Lower Manhattan Development Corporation (LMDC), an umbrella body set up by New York Governor George Pataki.

Nearly 3,000 people died in the attacks on the World Trade Center

The LMDC said the plans were aimed at "respecting the site as a place of remembrance facilitating continued revitalisation of Lower Manhattan".

As well as incorporating a memorial to nearly 3,000 people killed in the attacks, the designs include plans for open spaces and office buildings.

None of the six proposals include buildings as high as the former 110-storey twin towers.

Public debate

Groups representing victims' families led the drive for a permanent memorial.

Victims' relatives want a permanent memorial

"Where Tower One and Tower Two stood is sacred ground," said Joseph Maurer, whose daughter, Jill Campbell, died in the suicide attacks.

"It's the same as Gettysburg or Pearl Harbour," he said.

The proposals will be subjected to vigorous public debate over the next few months.

Three of the plans will be discarded by September.

New York Mayor Michael Bloomberg said he wanted to "strongly encourage everyone to use these plans to think about how the site should be rebuilt and then share their ideas with the organisations involved, as I plan to do".

The Port Authority of New York and New Jersey - which owns the site - said the final plans could incorporate elements from all six designs.