The British Chancellor of the Exchequer, Mr Gordon Brown, says he will complain to the European Union this week over its allocation of government contracts.
The chancellor in an article in the Timestoday said the allocation of European public works contracts, estimated by newspapers to be worth £1 billion each year, was "penalising enterprising and innovative companies".
Mr Brown commissioned a report last December into whether British companies are at a disadvantage when seeking public-sector contracts in the EU.
The Times, citing leaked extracts, said the report will conclude that the EU's single market has big failings.
The system is intended to ensure that goods, services, people and capital are able to move freely within the 25-member bloc.
The Timessaid the report from Mr Alan Wood, chief executive of the engineering group Siemens, will describe the market as too complicated, dogged by national preferences and lacking in open competition.
"We found a fairly consistent picture of British firms finding barriers and difficulties in their way," Wood was quoted as saying in the Times.
The newspaper said Mr Wood will highlight how contracts are awarded to local firms, even when foreign companies offer a better price or higher quality.
Brown will this week demand that the EU opens up the market to "fair competition," the Times said.
"People right across Europe will want to know why their governments are paying over the odds for services and equipment simply because they have refused to open up their markets and promote competition," Brown will say on Tuesday, according to the Times.
The Timesarticle also said that he will call for changes to the EU's state aid system. "In the interests of competition and enterprise, I will also push for urgent reform of the expensive state aid system," Mr Brown wrote.
A Treasury spokesman said the government would not comment on the contents of the Wood report ahead of its release, which was expected later today.