A MAJOR alert was sparked in York today when bank staff opened a package to discover a suspicious white powder.

A massive emergency service operation was mounted with officers sealing off part of the city centre.

Expert chemical, biological, radiological and nuclear advisers from the fire, ambulance and police services worked to determine what the substance was, treating the incident as a "worst case scenario".

Its content was still unknown as the Evening Press went to press.

Staff at NatWest Bank in Market Street raised the alarm just before 9am after returning from the Bank Holiday break.

Sgt Neil Hallewell said: "NatWest Bank received a package over the weekend. Staff opened it up this morning and found it contained some white powder. There were concerns about what the powder was.

"They placed that in an isolated room at the bank. A couple of members of staff who handled it were kept isolated at the bank in a room. We are going through the process of decontaminating staff who have been close to the package."

As the drama unfolded, firefighters in decontamination suits investigated the mysterious parcel behind the bank as four teams of firefighters as well as police and the ambulance service assisted.

The operation closed shops and parts of Market Street and Coney Street during the morning.

Crowds of onlookers gathered by police tape to watch as temporary decontamination showers were set up by the fire and ambulance services outside Woolworths.

The investigation continued as shop staff watched events from the windows.

Workers at H Samuel Jewellers in Market Street were told by police that the incident was "nothing to worry about".

At noon, a paramedic led two members of staff in decontamination outfits from the building into special decontamination showers.

The building may also have to be decontaminated when experts determine what the substance was.

Bystander Luke Hemingway, 25 said: "We got told there was an airborne chemical scare in the Nat West Bank. I work in Track Records and the owner's wife works in the jewellers on the corner and they were evacuated. It is not the kind of thing you see every day."

Updated: 14:53 Tuesday, March 29, 2005