It follows news that the Co-op is launching a two-year fixed mortgage at 1.09%, said to be the lowest rate ever.
Two weeks ago HSBC announced a five-year fix at a record low of 1.99%.
But experts say borrowers need to look closely at the fees involved, and the rates people will be charged when the fixed-rate period is finished.
Anyone wanting to take out one of the above mortgages will have to pay a fee of Â£1,500.
The average fee for taking out a mortgage is only Â£920.
"These rates come at a cost," said Rachel Springall of Moneyfacts.
"If you think you are going to have to move your mortgage again in two years time, you've got to think whether you are going to have to pay another fee," she told the BBC.
The Co-op's rate of 1.09% is only available to borrowers with a 40% deposit.
Customers are also being warned about the so-called "reversion rate" -  the interest they will be charged at the end of the fixed-term period, if they don't move elsewhere.
In the case of the Co-op, the reversion rate is a relatively high 4.74%.
Some experts believe mortgage rates could go even lower still.
"We're going to see a few months yet of this price war," said Rachel Springall.
Economists expect the Bank of England to maintain base rates at their current low of 0.5% until February 2016.
Mortgage rates are expected to rise as that date approaches.
Homeowners wanting to take advantage of tumbling mortgage rates are being warned to look out for high fees attached to them.