Five people from the West Midlands have been arrested after Chinese artefacts worth almost £2 million were stolen from a museum in Durham last week.
An 18th century bowl and a porcelain figurine were taken from Durham University's Oriental Museum on Thursday.
Police investigating the burglary say it was a "well-planned' and 'highly organised' job.
The bowl dates from 1769 and has a Chinese poem written inside.
The figurine of seven fairies in a boat stands around 30cm high. Both are from the Qing Dynasty, China's last imperial dynasty (1644 -1912). Their current whereabouts are unknown.
The senior investigating officer, Det Supt Adrian Green described the break-in:
"They have spent around 40 minutes creating a hole in an outside wall and when it has been big enough, they have entered the gallery and made straight for these two items.
I am sure this job has been planned for quite some time and I would think the artefacts have been stolen to order, for someone who has already identified a potential market."
One man, a 27-year-old from Walsall in the West Midlands is currently under arrest on suspicion of assisting an offender. He is being interviewed at a police station in County Durham.
Four other people from the same area – men aged 56, 41 and 36 plus a 34-year-old woman – were arrested at the weekend on suspicion of conspiracy to commit burglary.
They have all been released on police bail until early June pending further enquiries.