One thief can be seen with the painting tucked under his arm

The work, Madonna with the Yarnwinder, was stolen from Drumlanrig Castle, Dumfries and Galloway, on Wednesday by two men posing as visitors.

The images released on Friday include an e-fit of a man who bought the thieves' getaway car about two weeks ago.

Police were conducting forensic tests on the vehicle, a Volkswagen Golf GTi, which was found abandoned in woodland east of the castle on Wednesday evening.

There are also images of the thieves captured on the CCTV system inside the ancestral home in which the pair appear camera shy.

Another image shows the thieves making their escape, speeding away down the castle's drive with two accomplices in the car.

Previous visit

The painting, valued at between �25m and �50m, is one of the most important stolen in the last 70 years.

The suspects overpowered a female member of staff and escaped with the painting.

The suspects cover their faces

A police spokeswoman said: "The images taken from the Drumlanrig Castle CCTV system show the men involved in the theft of the painting.

"They can be seen making efforts to conceal their facial features."

Descriptions of the two thieves have been issued;

• the first was in his early 40s, 5ft 10in, clean shaven and of slim build

• and the other was in his late 40s, 5ft 10-11in, of slim build and clean shaven.

Police are continuing to carrying out forensic tests on the car. They are also searching for a second vehicle.

Fine arts loss adjuster Mark Dalrymple said the painting's value should not be underestimated, with some likening it to the theft of the Mona Lisa.

There is now a �100,000 reward for the safe return of the picture which was stolen in its frame.

A police computer generated image of one of the thieves

Dumfries and Galloway Inspector Phil Stewart said he believed the robbers had been to the castle before.

The da Vinci work, which experts say was painted between 1500 and 1510, depicts the Madonna with the infant Jesus holding a cross-shaped yarnwinder, symbolising the crucifixion of Jesus.

Drumlanrig Castle is home to the Duke of Buccleuch, who is one of Scotland's richest men.

The Renaissance master's painting was bought in Italy in the 18th century by the third Duke of Buccleuch.

Airports, ports and railways across the country have been made aware of the theft and given descriptions of the thieves.