Sussex will come to a standstill today to remember those killed and injured in the terror attacks on London.

Thousands of people will pause at noon to pay tribute to the victims of the blasts.

Many are expected gather in town centres and in front of public monuments to show their solidarity for those caught in the explosions last Thursday.

Public events for those who want to unite in mourning will be held outside Eastbourne Town Hall and at Priory Meadow Shopping Centre in Hastings.

Across Europe, millions of people are expected to observe a two-minute silence at noon UK time.

Londoners were urged to pour on to the streets in a demonstration of grief.

Prime Minister Tony Blair is expected to mark the silence at Downing Street while Culture Secretary Tessa Jowell will be at the family support centre in the Royal Horticultural Halls,Westminster, set up for people directly affected by the outrage.

Gatwick airport operator BAA said that, if at all possible, there would be no take-offs or landings.

Network Rail said no trains would depart from London stations at noon.

In Sussex, the day of mourning has been made more poignant after it was revealed that a University of Sussex graduate is among those missing following the explosions.

Fiona Stevenson, 29, who until recently was doing voluntary legal work in Belize, has not been seen since she left her London home for work on Thursday morning.

Her family are waiting to hear if she has been identified as one of the dead. The university's vice-chancellor said staff and students were shocked and saddened by the news.

Brighton and Hove City Council has said its staff will be free to observe the silence and Union Flags will remain at half mast on main council buildings for the rest of the week.

East Sussex and West Sussex County Councils will also invite employees to recognise the silence while schools in East Sussex have been notified and thousands of pupils are expected to join the tribute.

Books of condolences for the bombing victims opened at Brighton Town Hall and Hove Town Hall yesterday and people will be able to sign them between 8.30am and 5pm on weekdays for the next couple of weeks or for as long as there is a demand.

In Uckfield, town council staff at the Civic Centre will stop work at noon.

In Eastbourne, Mayor Graham Marsden will join council colleagues on the steps of the town hall in Grove Road to honour the dead and the maimed.

He said: "The horrific explosions in London last Thursday are an all too vivid reminder that global terrorism knows no bounds.

"I hope residents will either join members of the council at the town hall at noon or mark the period of silence in their own way."

In Hastings, people will gather at Priory Meadow Shopping Centre to stand for two minutes in sombre reflection.

Worthing Borough Council is also calling on people to observe the silence. Mayor Nick John has sent a letter of condolence on behalf of the town to Tony Blair.

Professor Alasdair Smith, vice-chancellor of Sussex University, has sent a message of sympathy to Miss Stevenson's parents, Ivan and Emer, and her younger sister Andrea.

In a statement, the university said: "All those who knew Fiona, taught her and studied with her will be shocked and saddened by the news that she is missing following the attacks in London.

"Our vice-chancellor has written to her family expressing the university's heartfelt sympathies and wishes.

"We are observing the national two-minute silence on campus. Fiona and all those affected by these terrible events will be very much in the thoughts of staff and students."

Fiona, who wanted to be a lawyer from the age of 14 and dreamed of working for the UN, graduated from Sussex in 1997 and kept in touch with friends in the county.

She left her home at the Barbican at 8.20am on the morning of the bombings to go to work but never arrived. Her family, who live in Essex, have not heard from her since.

An Essex Police spokesman said: "Although they still live in hope that she is alive, as the days tick by they are having to face up to the likelihood that she was one of those who so tragically lost their lives."

A statement issued by the police said: "Fiona always had a strong sense of right and wrong and was passionate about human rights.

"Since the age of 14 she had wanted to be a lawyer and had a long-term ambition to work for the UN so it was no surprise when she qualified in 2000 as a solicitor.

"She had recently put her legal skills to honourable use, working voluntarily for four months in Belize, and had only returned to England at the end of May.

"Work did not overshadow the fun-loving side of Fiona, who adored diving and whilst in Belize had completed two diving qualifications and a dive in the Blue Hole. She also competed in the 180-mile-long Ruta Maya four-day kayak race.

"She has been described as articulate, strong-willed, vibrant, energetic, caring, generous and, as her friends and sister always said, she never held a grudge.

"If Fiona's family receive the confirmation that Fiona died in last week's atrocities they and her friends will be devastated - Fiona is irreplaceable."