The government has rejected calls to force medium-sized companies to reveal their gender pay gaps.

As of 2017, firms with more than 250 employees have to publish figures about their gender pay gap. This leaves half of the UK workforce without knowledge of their workplace’s gap.

The business, energy and industrial strategy committee (BEIS) published a report in August that called on the government to be “more ambitious” with its new gender pay gap reporting regime. It recommended that all companies with more than 50 employees be forced to report their pay gap from 2020.

In a response published on Thursday, the government said that the threshold to qualify for gender pay gap reporting regulations was consulted on prior to 2017 and that over half of respondents agreed with the 250 threshold.

“Given the range of metrics required, it was felt that reporting could be particularly burdensome for small and medium-sized businesses and so the requirement should be restricted to large employers,” the response said.

The government said that gender pay gap figures for smaller organisations were unreliable as they were more sensitive to small changes like people leaving and pay rises. It added that it would consult on the feasibility of changing the threshold if there was appetite after this reporting year.

The committee’s report also recommended that the pay of company partners be included in gender pay gap reporting, saying “the exclusion of the highest paid people in organisations makes a nonsense of efforts to understand the scale of, and reasons behind, the gender pay gap”.

The government response said: “The regulations exclude partners in traditional partnerships and limited liability partnerships from the gender pay gap calculations, because partners are not ‘paid’ but instead take a share of the profits, which is not directly comparable with employees’ pay.”

It added that while there would be no changes this year, they were looking at clarifying the reporting guidance on partner pay in future years.

Commenting on the government response, Rachel Reeves, Chair of the BEIS select committee, said: “Next year is the 50th anniversary of the Equal Pay Act, and yet still we are tackling issues around fairness in pay. The UK has one of the highest gender pay gaps in Europe.

“Pay reporting can only be the first step in closing this gap and moving towards genuine equality and diversity in the workplace.” She said that the government’s decision not to accept their recommendations showed they were “timid in holding businesses to account for their efforts in driving the change needed”.

Penny Mordaunt, minister for women and equalities, said in the first year of mandatory gender pay gap reporting, over 10,000 employers had reported their data, as had 100% of those required to do so by law.

“Our world-leading reporting regulations have a crucial role to play in increasing transparency,” she said. “By driving board-level discussions on this issue the reporting process will push employers to take real steps towards closing the gender pay gap.”

According to figures lodged with the government, the worst offenders for women’s median pay gap included: Ryanair (71.8%), JP Morgan (54%), Capita Resourcing Limited (50.8%), Clarins (UK) Limited (49%), Merrill Lynch International (46.7%), EasyJet (45.5%), Sainsbury’s Bank (45.3%), Barclays Bank (43.5%) and Specsavers (41.9%).