Ireland's EU Commissioner Máire Geoghegan-Quinn has signed a letter calling on the next Commission President Jean-Claude Juncker to appoint "at least ten women" to the Brussels Commission.

The letter, which has come from the outgoing female commissioners, is designed to put pressure on national governments to put more female nominees forward.

Nine out of the 28 current commissioners are female.

During his campaign to become commission president, the former Luxembourg prime minister Jean-Claude Juncker indicated that he wanted 40% of the new commission to be made up of women.

That would mean 11 female commissioners in total.

However, of the 11 candidates either confirmed or suggested by national capitals so far all are men.

Some commission officials warn that if Mr Juncker fails to get at least nine women into the college of commissioners, his nomination as president could run into difficulty during next week's vote by the European Parliament in Strasbourg.

The letter written by the outgoing female commissioners states: "The European Union is committed to making continual progress towards gender equality.

"Such progress demands an increase, not a decrease in the number of female Commissioners, particularly as we have grown to be a family of 28 Member States.  

"We therefore urge Member States to nominate at least 10 female Commissioners, with your support." 

Ultimately it is up to national governments to nominate candidates. 

However, according to officials, the letter is designed to give president-elect Mr Juncker some leverage in encouraging more capitals to put forward women nominees.

It is understood that Mr Juncker, whose nomination as commission president was fiercely opposed by the British prime minister David Cameron, could promise heavyweight portfolios to those member states who nominate a female commissioner.

According to the Europolitics website, there are some 70 prominent women with political experience across all 28 member states.

The website mentions Fine Gael MEP Mairead McGuinness as a strong female candidate should the Irish government decide to send another woman commissioner to Brussels.

The website writes that Ms McGuinness, "a former journalist… has been an MEP since 2004 with strong expertise in agricultural policy and was recently elected a Parliament vice-president".