Boots has insisted it remains “committed” to reducing the price of emergency contraception after it emerged the retailer had cut prices in just 3% of stores.

The pharmacy giant bowed to public pressure last summer and pledged to slash the price of the morning after pill from £26.75 to £15.99, having previously said that lower prices encouraged women to have unprotected sex.

But five months after that promise, Boots has admitted prices have been reduced in just 69 of its 2,500 stores across the UK.

The retailer blamed low stock levels for the delay in introducing the new price point.

The British Pregnancy Advisory Service (BPAS), which led the initial campaign for Boots to bring its prices in line with other pharmacies, said it was “absolutely scandalous that Boots have failed to deliver on the clear pledge they made to roll out cheaper emergency contraception in all their stores”.

The criticism comes after a letter signed by more than 130 MPs expressed disappointment that the cheaper prices had not been rolled out more widely.

The letter, written by shadow minister for public health Sharon Hodgson, said “many women struggle to access contraceptive services and their usual family planning method. As a result, the British Pregnancy Advisory Service reports that they see an increased number of women facing an unplanned pregnancy following the festive season.

“Clearly, pharmacy access to emergency contraception is of an even greater importance in December and January.”

Boots does offer a free NHS service for emergency hormonal contraception (EHC) in the majority of its stores.

To be eligible for the free morning after pill, customers must have a prescription from their GP or a family planning clinic.

A spokeswoman for Boots said: “We remain committed to rolling this service out nationally.

“Unfortunately, the manufacturer has experienced a batch failure due to quality issues which means that the stock we were expecting is not now available, and we are now waiting for a new batch to be produced.

“We thank our customers for their continued patience and reassure them that we are doing all we can to roll this service out to all our stores as soon as possible.”

But in a strongly-worded statement, the BPAS insisted that was “absolutely no excuse” for what it dubbed a “pathetically slow pace of progress”.

It added: “If Boots cannot source a new version of emergency contraception to sell at a lower price, then they should do the right thing and cut the price of the version they currently have in stock.

“Regardless of supply chain delays, affordable emergency contraception is entirely within their gift to give right now – and every day they refuse to do so, more women are being ripped off, or risking an unplanned pregnancy because they cannot afford Boots’ inflated price tag.”

Even after lowering prices to £15.99, Boots’ morning after pill is still £2.49 more expensive than products sold by a host of its rivals, including Superdrug, Tesco, Asda and Morrisons.