By Alex Webb BBC News Online entertainment staff

Finding words for an event like the attacks of 11 September is not easy.

Politicians reach for clichés, journalists are inclined to waffle, and even poets and novelists stumble.

It is characteristic of actor and author Steven Berkoff that he should be undaunted by the enormity of the events, and want to pay his own tribute to what he calls its "unknown victims".

At London's Riverside Studios on Wednesday the actor - known for his taste for the Gothic and his background in Shakespeare and Kafka - proved equal to the task.

Berkoff refreshed the horror of images gone stale through repetition

His Requiem For Ground Zero is a 550-line performance poem and has been performed just once before, at the Edinburgh Festival.

The setting was a bare studio, and the small audience the sort of well-spoken, mildly trendy crowd you might expect for a piece of contemporary theatre.

Berkoff emerged in black and, without any introduction, started painting a verbal picture of the tranquil "blue-skied Tuesday" which preceded the attacks on the World Trade Centre.

In natural-sounding, subtly rhymed lines he conjured a whirl of images of New York that morning, awaiting its rendezvous with "the man in seat 8D" - Mohammed Atta.

Silence

"What goes through the hearts and minds of men in mighty stress?" the poem asked.

By now the momentum of the work and the gravity of the subject matter had created a deep silence.

Moments of black humour passed, but it seemed no one dare laugh.

There were moments of dark humour

Part recital, part mime, Berkoff's performance succeeded in refreshing the horror of images which have started to go stale through repetition - the last calls to loved ones, the moments of impact, the diving bodies.

"Could we ever imagine such things to be?" he asked.

The final cadences of the work were lighter - his mimicry of Bush and Blair was accurate enough to draw a big laugh out of the audience - and he finished by repeating the phrase "let's have some understanding, too".

There was a noticeable pause before anyone clapped.

"What I tried to do was make a memorial," Berkoff told BBC News Online.

"America is like a younger brother of ours, so we're almost Americans, and the only way I could deal with this was to write it down.

"But I though I had to make some kind of extra effort, not just sit there and read, so I learned all 550 lines - it took me about four or five months.

"Sometimes just setting down what happened is the most powerful thing you can do," he said.

And for the audience at the Riverside - people perhaps uneasy with the formal commemorations of the day - this may have been a better way to remember the 3,000 dead of 11 September 2001.