LONDON, Nov 1 (Reuters) - Novo Nordisk has hired FUJIFILM Diosynth Biotechnologies to fill Wegovy injection pens, a source familiar with the matter told Reuters, as the Danish drugmaker scrambles to boost output of its hugely popular weight-loss drug.

FUJIFILM Diosynth Biotechnologies, a subsidiary of Japan's Fujifilm Corp, is the third contract manufacturer Novo has hired to fill Wegovy pens - in addition to Catalent and Thermo Fisher - as it spends billions to ramp up production to meet skyrocketing demand and ease shortages.

The company will do the filling work at its site in Hillerod, Denmark, the source said, declining to be named because the information is confidential. It was not clear when the work would start nor how much the deal was worth.

Spokespeople for FUJIFILM Diosynth Biotechnologies and Novo, which become Europe's most valuable company in September, did not immediately respond to requests for comment.

FUJIFILM Diosynth Biotechnologies CEO Lars Petersen told Reuters last week that it expects to announce by the end of this year a major contract for sterile fill-finish.

Wegovy is the first-to-market in a new class of highly effective weight-loss drugs. Used alongside changes to diet and exercise, it leads to an average weight loss of around 15%.

The weekly weight-loss injections belong to a class of drugs known as GLP-1 agonists, which analysts estimate could be worth as much as $100 billion within a decade, including oral treatments now being developed by Pfizer and others.

Sales of Wegovy have soared since its launch in the United States in June 2021 and Novo, which is expected to report record profits for the third quarter on Thursday, has warned U.S. demand will outpace supply into next year.

Eli Lilly's Mounjaro is also expected to be approved for weight-loss in the United States this year.

(Reporting by Maggie Fick; Editing by Josephine Mason, Kirsten Donovan)