High street goods are unlikely to become massively cheaper if Britain joins the euro, experts believe.

The prices we pay for good and services will be affected by entry into the euro and was a key part of the Treasury's assessment.

Consumers have long questioned why many products, such as cars and clothes, can be bought cheaper in Europe.

Fears were also raised by people in Europe that when the euro took over, prices would rise.

As manufacturers have long argued, being outside the euro means there is an extra cost of exchange rates that has to be brought into calculations.

But the Treasury concludes the euro would not lead to cheaper goods because of transport costs, local taxes and wages differences.

"Remaining price differentials are likely to vary across sectors. Price convergence is likely to take a considerable amount of time," they warn.

It finds euro entry could increase competition and allow British firms to enter new markets but there is also a problem.

Brown's team warns other EU reforms would have to take place - such as creating well-functioning markets - for Britain to get the benefits in full.