SNP ministers have been accused of a "cynical abuse of power" after keeping secret for three months a catastrophic error that meant hundreds of women were wrongly excluded from a cancer screening programme.

Alex Cole-Hamilton, the Scottish Liberal Democrat health spokesman, said Nicola Sturgeon’s Government had "deliberately hidden from the public" the cervical cancer screening blunder after finding out about it in March.

Maree Todd, the Women’s Health Minister, finally went public with the scandal in a parliamentary statement on Thursday only hours before the start of Holyrood’s two-month summer break.

Jackie Baillie, Scottish Labour’s health spokeswoman, said the affected women deserved to be told immediately and noted that cancer screening was raised repeatedly during the recent Holyrood election campaign, but Ms Sturgeon "did not say a word".

She said the SNP’s decision to "keep the public in the dark on such a serious mistake beggars belief" and concluded: "It is hard to see this as anything other than playing politics with people’s health."

434 women wrongly told there was no need to be screened

Ms Todd admitted that 434 women who had undergone partial hysterectomies were wrongly told there was no need for them to be checked. A small number went on to develop cervical cancer and one died, with mistakes dating back to 1997.

However, she admitted that the tally of women who developed cancer may increase, telling BBC Scotland: "I’m afraid we may well be looking at higher numbers."

She vigorously denied any cover-up, saying that there was a "laborious process of going through their records" to identify the women before the scandal was made public.

The minister said all the women affected were contacted by letter on Tuesday and that "we did not want to cause undue anxiety and stress" by revealing the error earlier.

It was initially identified by an audit in December last year after an unidentified NHS board discovered women who had developed cervical cancer after being wrongly excluded from screening.

An urgent case review going back 24 years was launched that discovered hundreds of other cases. While most patients undergoing a hysterectomy have their cervix removed completely, some have a "sub-total hysterectomy".

At least 500 older cases still need to be investigated 

Part of the cervix can be left behind, meaning they still require to be screened for cancer. The 434 cases so far identified of women wrongly excluded from screening occurred after 1997, but the records of at least 500 older cases still need to be checked.

A further 170,000 women who had hysterectomies are having their case notes reviewed as a "precaution" to see if they were also wrongly excluded from screening but the "vast majority" are not expected to be affected.

Mr Cole-Hamilton said: "SNP ministers had knowledge of these fatal errors before the elections. I was shocked when the minister said they had known about this since March.

"It is a cynical abuse of power to only disclose this serious adverse event months later and on the afternoon when Parliament breaks up for the summer. It is an insult to the women who were failed by the errors in this screening programme."

Pressed why the Scottish Government had not disclosed the scandal earlier, Ms Todd said: "We had a number of issues that we had to follow and I didn’t want to put it in the public domain before we had notified the women.

"So on Tuesday this week we sent letters to all of the women affected, and to their GPs to ensure that they could have access to good information once they became aware that they were affected."

She insisted it was not a "fair criticism at all" to say SNP ministers had "sat on" the information as going through the women’s records was a "laborious process".

Ms Todd said records from before 1997 were more difficult to access, but that the work should be completed in July and the women contacted in August.

She said she had offered to meet her opposition shadows during the summer recess so they can "ask more questions" and receive briefings from clinicians.