The far-right British National party has agreed to change its constitution to allow non-white people to join, it emerged today.

The BNP confirmed it would consider changes to its rules and membership criteria after the Equality and Human Rights Commission launched county court proceedings against the party's leader, Nick Griffin, and two other party officials: Simon Darby and Tanya Jane Lumby.

Robin Allen QC, counsel for the commission, said Griffin had agreed to present members with a revised constitution at its general meeting next month.

He added that the party had agreed not to accept any new members until the new constitution was in place.

John Wadham, group director legal at the Equality and Human Rights Commission, said: "We are pleased that the party has conceded this case and agreed to all of the commission's requirements. Political parties, like any other organisation are obliged to respect the law and not discriminate against people.

"It is unfortunate that the BNP spent several months before conceding and dealing properly with our legal requirements. We will be monitoring the BNP's compliance with this court order on membership, and its other legal obligations, including to its constituents."

The Central London county court heard Griffin would be given 10 days to submit a signed undertaking confirming the proposed changes.

The case has now been adjourned until 28 January to allow the BNP to comply.

It is understood that the BNP regarded the action as an attempt to bankrupt the party. Chris Roberts, the party's eastern regional spokesman, said it was too early to say how the proposed rule change would affect its membership: "I cannot speculate as to who will join our party when our constitution changes.

"I just believe its another obstacle thrown into our way by the Lib-Lab-Con elite that now we are taking votes from them they are trying to put us out of business."

During the case, the commission argued it had a statutory duty, under the Equality Act 2006, to enforce provisions of the act and to work towards the elimination of unlawful discrimination. This duty includes preventing discrimination by political parties.

The commission sent a letter on 22 June 2009 to the BNP setting out its concerns about its constitution and membership criteria which appear to restrict membership to those within what the BNP regards as particular "ethnic groups" and those whose skin colour is white. This exclusion is contrary to the Race Relations Act, which the party is legally obliged to comply with.

The commission asked the BNP to provide written undertakings it would amend its constitution and membership criteria to ensure, and to make transparent, that it does not discriminate against potential or actual members on racial grounds.

In an order issued at the Central London county court this morning, the BNP agreed to use all reasonable endeavours to revise its constitution so that it does not discriminate, either directly or indirectly on any "protected characteristic" – for example on the grounds of race, ethnic or religious status – as defined in clause 4 of the equality bill.

The changes must be carried out as soon as reasonably practicable, and no later than three months from today.