About 4,000 people work in the building

Union officials said they would ensure staff in the mail room were happy with new arrangements after a parcel bomb injured four people last Wednesday.

The Public and Commercial Services Union (PCS) said the DVLA had responded to all of its concerns to date.

Police are looking into seven mail bomb attacks on businesses since 18 January.

A 48-year-old man, held by detectives after telling a radio station he had sent one of the devices, has been eliminated from the inquiry.

There is nothing that we have asked then to do that they are not doing Peter Harris, PCS

One woman suffered minor burns and two men and a woman were treated for hearing-related injuries following the explosion in the post room of the DVLA's Swansea offices shortly after 0920 GMT last Wednesday.

Peter Harris, PCS officer for Wales, said: "In effect there have been discussions every day since this took place.

"I'm happy with the actions taken on Thursday and Friday last week. There is nothing that we have asked then to do that they are not doing.

"We do need to constantly review the situation and today we are trying to get feedback from local reps not just in Swansea but other offices from the people who are working at the sharp end."

He said if members still had concerns the union would try to address them straight away.

Around 4,000 people work at the offices in Swansea which maintain UK-wide registers of drivers and vehicles.