Women discriminated against by employers because they are pregnant or because they are mothers, must be better protected by the employment tribunals system, according to a powerful Westminster Committee.

The Justice Committee called for changes in a report today after carrying out an inquiry into the impact of changes to court and tribunal fees.

According to campaigners, there has been a 40 per cent drop in claims for pregnancy-related discrimination or dismissal, since the introduction of fees.

The Committee's report backed their concerns about fees and included damning criticism of the Conservative Government for failing to research the likely impact of the charges before they were introduced and then delaying publication of evidence of their impact.

Recommendations in the report include a substantial reduction in fees overall, and special consideration for the position of women alleging maternity or pregnancy discrimination. MPs also said a time limit of three months for women wanting to bring such a claim should be reviewed.

Overall, the introduction of fees for claimants in employment tribunals since July 2013 has led to a drop of almost 70 per cent in the number of cases of all types brought, the Justice Committee's report says.

While MPs on the committee agreed that some kind of financial commitment was necessary to avoid frivolous or vexatious cases being brought, it question whether amounts currently being charged are acceptable or a barrier to justice.

The report backs the view of Lord Dyson, master of the Rolls, who said the quality of research carried out by the Government prior to the changes was "lamentable", the chair of the Bar Council who described it as "insignificant" and the President of the Law Society who said it was "poor".

Even after the policy was introduced, the report says, too little has been done to assess its impact. Findings of a post-implementation review have still not been reported a year after a review began and six months after they were due to be published.

Committee Chair Bob Neill MP said: “We understand the financial pressures on Ministers. We also understand that the MoJ does not always have the luxury to be as rigorous and meticulous in preparing the ground for controversial policies as it might wish. But it is important that in such circumstances the Ministry ... does not represent the quality of its evidence base to be higher than it is.”

He added: “The timing and scale of the reduction following immediately from the introduction of fees can leave no doubt that the clear majority of the decline is attributable to fees.”

The report was greeted with delight by former Dumbartonshire East MP Jo Swinson, in her new role as chair of the charity Maternity Action.

She said: "Employment tribunal fees reduce access to justice for all employees and impact particularly harshly on new mothers. The Justice Committee has rightly recommended special consideration of the position of women reporting pregnancy and maternity discrimination.

"Employment tribunal claims do not just benefit the women who bring them. Enforcement of laws protecting pregnant women and new mothers at work are fundamental to achieving gender equality."

Sarah Jackson OBE, Chief Executive of Working Families also welcomed the report. She said: "We hear from women experiencing maternity and pregnancy discrimination every single week. There’s no doubt that tribunal fees have stopped women who’ve been mistreated at work from pursuing the justice they deserve."

A Ministry of Justice spokesman said: "We welcome this report and will consider the findings carefully.

"The cost of our courts and tribunal system to the taxpayer is unsustainably high, and it is only right that those who use the system pay more to relieve this burden. Every pound we collect from fee increases will be spent on providing a leaner and more effective system of courts and tribunals.

"At the same time, we've made sure that the most vulnerable and those who cannot afford to pay won't have to."