Eversheds is in talks with US firm Foley & Lardner as the UK firm continues its push to secure a merger across the Atlantic.

Legal Week understands that the pair – which have operated a referral relationship for at least four years – have been discussing a more formal combination in recent months.

Milwaukee, Wisconsin headquartered Foley has 17 offices across the US and nearly 900 lawyers. It has international offices in Brussels, Shanghai and Tokyo.

Sources close to the firm have also said Eversheds has been speaking to at least one other US firm in its hunt for a merger partner.

They indicated Eversheds had previously approached Chicago's Seyfarth Shaw among others, although Seyfarth denied any merger discussions had taken place.

A spokesperson for Seyfarth said: "We were never part of those talks and it would be inaccurate to suggest otherwise."

According to The American Lawyer, Foley is the 47th largest law firm in the US, with revenue of $665m (£434.63m). It has 849 lawyers and 153 equity partners.

By contrast Eversheds is the 13th largest law firm in the UK, with a 2014-15 revenue of £380.7m and an average profit per equity partner (PEP) of £741,000. The firm has 1,211 lawyers, and 332 partners, of which 118 are equity partners.

A combination between the two could create a firm with revenue of around £815m ($1.25bn), placing it on the fringe of the global top 20.

Eversheds has made no secret of its desire to merge with a US firm. Its partnership voted to back the strategy at the firm's June 2014 partner conference and its chief executive Bryan Hughes confirmed that the firm was looking to move to a shortlist of two to three potential merger candidates by early 2015.

The firm, under the stewardship of Hughes, has stated that its aim is to be global by 2020.

An Eversheds spokesperson said that the firm's intention to "establish a presence in the United States" was "well documented" and that the firm's "investigations continue in this respect".

He added: "A number of options remain open to us and until we are clear on the way forward it would be wholly inappropriate to comment further."

Eversheds is also thought to be interested in growing domestically, with its London corporate practice an area that it is particularly interested in strengthening. There have previously been suggestions that an approach was made to Addleshaw Goddard, although both firms declined to comment on this.

A spokesperson for Addleshaws said that there was nothing they wished to say as the firm "won't comment on speculation and rumour".

Foley & Lardner did not respond to requests for comment.