The European Union's justice commissioner, Viviane Reding, is expected to set aggressive quotas and timetables on Monday to increase the number of women on the boards of public companies.

Speaking to the Guardian before the announcement, Reding said that "it's no secret that in countries where there are legal quotas [for representation on boards], the figures have grown substantially. In countries without obligatory quotas, progress is slow."

She added that "Generally, progress is very slow", noting that at current rates it would take another 40 years for women to have equal representation on boards throughout Europe. "I think we're slowly running out of patience everywhere in Europe," she said.

Reding warned companies last year that she would begin steps to introduce legislation this month if she found progress to be insufficient. She is due to publish the statistics from analyses of board membership, but indicated that she didn't think that would be enough on its own.

On Thursday the European Round Table of Industrialists (ERT) published the results of 31 member companies' records of female representation in "leadership positions", which ranged from 28.5% at Ecazcibasi Group, a Turkish industrial group, to 4% at Denmark's Moller-Maersk.

Reding has called for European countries to set themselves a target of women making 30% of board members by 2015, and 40% by 2020. But so far only 24 firms have signed up. Asked to compare progress among EU member countries, Reding said: "There are countries which are doing better than others. There is a huge diversity in Europe … you have to see where you're starting from. If you start from 15% it's easier than if you start from 5%.

"What we'll measure [in Monday's report] is the progress which has been made on the basis of where a certain country starts."

But Reding was adamant that there are plenty of women capable of challenging at the highest level. "It's very interesting that the major business schools of Europe have united forces because they have seen that often the best MBAs are done by women, but the best positions after the MBA are taken by men. So the business schools decided to pool the talent which is available on the market – that means very qualified women who have a lot of management experience – in order to put this pool at the disposal of those who take the decisions on the fulfilling of the vacant positions on the board. Very often we have heard that the women are not available. They are," she said. "They are."

Reding praised the report published in February 2011 by Lord Davies on the same topic in the UK.

"I met a year ago with the CEOs of the large publicly listed companies. They told me they were capable of solving the problem by themselves.

"At the same time Lord Davies came out with his report in Britain with similar, not to say identical, figures and problems and blockings."

Now, she suggested, politicians were ready to take action, pointing to a speech by David Cameron in Stockholm in which he said that if progress on female representation did not speed up, "having strong measures will not be taboo any more".