Thieves made off with 'Sir William Chambers'

They are some of Britain's most prized public treasures, jealously guarded by the Government on behalf of the nation. But not, it appears, when they are placed in the hands of ministers, ambassadors and civil servants.

State-owned paintings worth hundreds of thousands of pounds have been lost, stolen or damaged while on loan to government departments in the UK and around the world over the past four years.

The Department for Culture, Media and Sport (DCMS) has admitted that 19 works from the Government Art Collection have been reported lost or stolen from buildings as far afield as Jakarta and Sao Paolo since 2005. (Four of these, including Strand on the Green by Rodney Burns, were later found elsewhere on the same premises.)

Twelve more were damaged and had to be repaired at a cost of thousands of pounds. Repairs to two works at 10 Downing Street, which included a portrait of Sir Robert Walpole (for "tears in the canvas – cause not established") cost £5,000 alone.

The DCMS is considering demanding compensation for the losses, recovery and repairs running into thousands of pounds.

But opposition politicians last night complained that ministers and officials were "too casual" with the 13,500 treasures in the Government Art Collection, which range from original works dating back to the 16th century to limited-edition prints. The Conservatives called for stiffer discipline to force staff to take more care with the valuable items entrusted to them.

"When people reach a certain level in public life, they are given access to the Government Art Collection, but this art still belongs to the public and it needs to be looked after," said the shadow Culture spokesman, Jeremy Hunt. "These figures suggest people are becoming far too relaxed about the art that is on loan to them."

Eight years ago, five paintings worth almost £250,000 went missing while the British ambassador to Argentina was moving to a temporary residence in Buenos Aires. The then Foreign Secretary, Jack Straw, pledged that his department took the safety of official premises seriously and was reviewing security at the embassy as a result.

The DCMS pushed for a financial penalty against the FCO to compensate for the losses but later dropped the issue. However, an inventory of the collection's missing works has revealed that more than half of the 27 instances of theft, loss and damage in this period happened at Foreign Office premises around the world. Six mishaps occurred at the department's main building in Whitehall.

Two paintings worth more than £80,000 were taken from Somerset House, in London, in February 2008. After a huge international police operation Shipping, by John T Serres, and Sir William Chambers, by Francis Cotes, were eventually recovered.

Several works were damaged because of problems with the paint or canvas, but in two cases the explanation was simple: "fell off wall".