Imposing “emergency measure” by raising security, The British Museum has fired a staff member after it found items from its collection missing.

It launched an independent investigation when it found some items missing, stolen and damaged including jewellery with semiprecious stone and glass dating from the 15 century BC to the 19 century AD.

Following the dismissal of a staff member, legal action has been taken against him and the matter is also being investigated by the economic crime command of the Metropolitan police.

The museum’s independent review, led by Sir Nigel Boardman, a former trustee, and Lucy D’Orsi, the chief constable of British Transport Police, will investigate and make recommendations on future security arrangements. It will also “kickstart a robust programme to recover the missing items,” the museum said.

Small pieces kept in the store room were included in missing items, belonging to one of the collections of the museum, which has not been displayed yet and they were kept for academic and research purposes.

“The trustees of the British Museum were extremely concerned when we learned earlier this year that items of the collection had been stolen,” museum chair George Osborne told The Guardian.

“The trustees have taken decisive action to deal with the situation, working with the team at the museum. We called in the police, imposed emergency measures to increase security, set up an independent review into what happened and lessons to learn, and used all the disciplinary powers available to us to deal with the individual we believe to be responsible.”

“Our priority is now threefold: first, to recover the stolen items; second, to find out what, if anything, could have been done to stop this; and third, to do whatever it takes, with investment in security and collection records, to make sure this doesn’t happen again.”

“This incident only reinforces the case for the re-imagination of the museum we have embarked upon. It’s a sad day for all who love our British Museum, but we’re determined to right the wrongs and use the experience to build a stronger museum.”

Hartwig Fischer, the museum’s director, said: “This is a highly unusual incident. We take the safeguarding of all the items in our care extremely seriously.”

“The museum apologises for what has happened, but we have now brought an end to this – and we are determined to put things right.”

“We have already tightened our security arrangements and we are working alongside outside experts to complete a definitive account of what is missing, damaged and stolen. This will allow us to throw our efforts into the recovery of objects.”

Boardman said: “The British Museum has been the victim of theft and we are absolutely determined to use our review in order to get to the bottom of what happened and ensure lessons are learnt. We are working alongside the Metropolitan police in the interest of criminal justice to support any investigations.”

“Furthermore, the recovery programme will work to ensure the stolen items are returned to the museum. It will be a painstaking job, involving internal and external experts, but this is an absolute priority – however long it takes – and we are grateful for the help we have already received.”

The museum denied giving further comments before completing the investigation.