Dutch studio OMA has announced that its long-standing partner Ellen van Loon is leaving after 26 years to "enter a new phase in her life".

Van Loon joined OMA in 1998 and became a partner in 2002, working on projects including the iconic CCTV Headquarters in Beijing, De Rotterdam "vertical city" development and, more recently, Aviva Studios events space in Manchester.

OMA announced Van Loon's retirement on its website earlier this week, stating that she decided to leave the studio to free up more time to begin a new chapter in her life.

Before her leave, she was the only woman out of eight partners at the studio.

"After 26 years of working with us, Ellen has indicated that she wishes to enter a new phase in her life in which she will have more time to herself," said OMA.

"It goes without saying that we deeply regret her decision," the studio continued. "Ellen has been a trusted colleague and powerful force within our firm for decades. She also is, and will remain, a dear friend to all of us."

Based in the Rotterdam office, Van Loon developed a portfolio including the Maggie's Centre in Glasgow and the New Court Rothschild Bank in London, which were both shortlisted for the Stirling Prize in 2012.

She also worked on the remodelling of the Rijnstraat 8 Dutch government offices, the Qatar National Library, a blocky glass development for the Blox architecture centre and co-working space in Copenhagen and the transformation of a 19th-century structure in Paris into a gallery for the Galeries Lafayette Foundation.

OMA was founded in 1975 by Dutch architect Rem Koolhaas alongside Elia Zenghelis, Madelon Vriesendorp and Zoe Zenghelis.

Recent projects completed by the studio include a bridge in Bordeaux intended to double as a public space and an early-1900s bakery in Detroit that was converted into an arts centre.