By Ian Youngs
BBC News entertainment reporter
Independent record labels may try to fix the UK singles chart this week in an attempt to prove it is not secure, according to a label boss.
The first Top 40 to include download sales will be revealed on Sunday
Downloads will count towards the Top 40 for the first time this week and chart authorities have said it will be safe.
But Guy Holmes, chairman of Gut Records, which has had success with Tom Jones, Space and Uniting Nations, said some labels could try to expose flaws.
"It's not a slight problem - it's a huge problem," he told BBC News.
He said the unnamed labels may attempt to download specific singles many times in an attempt to inflate their chart success.
They may choose songs released by other labels, including majors, to prove their point, he said.
"I know of two different labels who are considering buying records online because they believe it's the only way they can teach the chart people that the security of the chart is no longer there," he said.
"The people who have instigated the chart have failed dismally in their responsibilities to make and keep our charts secure and to stop people with large amounts of money being able to take advantage of it."
Legal downloads bought from eligible internet services are being added to sales of CD singles and other formats to compile the Top 40. The first new rundown will be revealed on Sunday.
Mr Holmes said it would take several thousand additional sales to push a song from number 20 into the Top 10 and onto Top of the Pops.
With songs costing about 79p-99p each online, that would be money well spent for some labels, he added.
Official UK Charts Company (OCC) charts director Omar Maskatiya warned any label caught chart-fixing could be banned from the chart.
"We will treat hyping in the digital world in exactly the same way as we do for physical formats," he said.
"We're pretty confident on the security front and obviously haven't taken that issue lightly."
Security systems are expected to look for the same credit card or mobile phone numbers buying multiple copies of the same song.
He added that eight months of running a separate download chart had given them a knowledge of buying patterns that will help them spot unusual activities.