CMS, Olswang and Nabarro have confirmed they are in discussions about a three-way merger that could create a firm with combined revenue of almost £1bn, including turnover from the global CMS network.

Partners at the three firms took part in a conference call earlier this morning, setting out the potential path to one of the biggest UK law firm mergers in recent years.

According to partners on the call, more details about the proposed union will be issued to partners in the coming days, with news of the talks ending months of speculation about the future of Olswang, which has been actively seeking a merger for years.

Its discussions with CMS's UK arm broke during the summer, but the proposed three-way union clearly represents a far bolder move.

Assuming the merged firm would also be part of the wider CMS network, it would be the eighth largest firm in the UK by revenue, sitting behind Norton Rose Fulbright and ahead of Herbert Smith Freehills.

Based on figures for Legal Week's UK Top 50 2015-16, the firm would have combined revenue of £978m and nearly 1,000 partners. CMS, Olswang and Nabarro posted profit per equity partner of £443,000, £490,000 and £586,000 respectively in 2015-16.

In a joint statement, the firms said: "The leadership consider this combination would create a differentiated modern firm that would combine scale with an exceptional depth of sector expertise. The combined firm would provide clients with a stronger and more global platform served by 65 offices across 36 countries, underpinned by a 250-year City heritage. There should be no assumption as to the outcome of these discussions and we  will update in due course."

All three firms have offices in London and Brussels, and there are also duplicate offices in Hong Kong, Madrid, Munich, Paris and Singapore. Elsewhere in the UK, Nabarro has offices in Manchester and Sheffield, CMS has an office in Bristol and across Scotland as a result of its merger with legacy Dundas & Wilson, while Olswang has a base in Thames Valley.

Commenting on the discussions, one former Nabarro partner said: "Nabarro had reached the ceiling in terms of turnover and partner numbers. They have an awesome real estate practice but could never fully break into the areas they wanted to, like corporate and finance. I think this will give them more opportunities in those areas."

An ex-CMS partner said: "Personally, I think it would be a good thing – CMS and Olswang's IP practice are both 'band one'. if I was still a partner at CMS, I would be voting for it. Olswang has obviously been going through a hard time but is still a good firm and would really benefit from CMS. I think they're all a really good fit for each other. I was excited when I read the news."

Three-way mergers are rare in the legal world, with notable examples including the 2013 combination of SNR Denton, Salans and Fraser Milner Casgrain, which created Dentons; Norton Rose's 2011 tie-up with Canada's Ogilvy Renault and South Africa's Deneys Reitz; and the 2005 merger of DLA with US firms Piper Rudnick and Gray Cary Ware & Freidenrich, which formed DLA Piper.

Nabarro held merger talks with Addleshaw Goddard in 2013, a deal that would have created a combined firm with revenues of more than £280m.