* Swiss company urges UK to act over drug supplies
* Says it is stockpiling medicines
* GSK, others also stockpiling drugs (Adds Roche, drug details)
By Kate Holton and Noor Zainab Hussain
Jan 25 (Reuters) - Novartis called on Britain to urgently guarantee the movement of drugs in the event of a chaotic Brexit and said it was stockpiling to maintain the delivery of the 120 million packs it exports to Britain from Europe each year.
The Swiss company, one of the world's biggest drugmakers, said the risk of Britain leaving the European Union, its biggest trading partner, without a deal had risen after Prime Minister Theresa May failed to get her deal through parliament last week.
"Given the complex nature of the supply chain, government needs to implement a comprehensive continuity plan rapidly," Novartis said here in a statement.
Novartis's fastest-growing medicine is Cosentyx, the blockbuster medicine for psoriasis and other auto-immune disorders including ankylosing spondylitis. It also makes the cell therapy Kymriah, for young people with leukemia, and the multiple sclerosis medicine Gilenya.
Fellow Swiss drugmaker Roche, which makes the cancer drugs Herceptin, Avastin and Rituxan, has also built up stocks to prevent any shortages.
Britain is due to leave the EU on March 29, and with May still battling to get the accord she agreed with the rest of the bloc through parliament, businesses are having to spend millions of pounds to prepare for a "no-deal" exit.
The highly regulated drugs sector is one of the most vulnerable to a no-deal outcome due to its pan-European supply chains and need for regulatory oversight.
More than 2,600 drugs have some stage of manufacture in Britain and 45 million patient packs are supplied from the UK to other European countries each month, while another 37 million flow in the opposite direction, industry figures show.
Britain has called for drugmakers to produce an additional six weeks of medicines to cope with potential supply disruption in the event of a no-deal Brexit - a target the industry has said would be challenging.
"It is vital that government makes minimising disruption to the medicines supply the highest priority as it prepares for a potential hard or disorderly Brexit and ensures cooperation over medicines regulation in this event," Novartis said.
Novartis also urged Britain's health service and pharmacists to stick to the government's advice not to stockpile medicines, so the supply can be managed centrally and not risk shortages.
Britain's biggest drugmaker GlaxoSmithKline has said it is increasing inventory, updating packaging, amending importation licences and securing warehousing to protect its supply chains before March 29.
It puts the cost of implementing such changes at 70 million pounds ($92 million) over the next two to three years, with ongoing costs of around 50 million pounds per year.
With parliament in deadlock, many major companies that normally avoid national politics have started to turn up the volume, with Airbus, the world's second-largest aerospace group, warning it could shift future wing-building out of the country in the absence of a smooth exit.
Airbus employs 14,000 people in Britain while Novartis, the maker of neurological, immunology and cancer drugs, employs around 1,500 in Britain. ($1 = 0.7642 pounds)
Reporting by Noor Zainab Hussain in Bengaluru; additional reporting by John Miller in Zurich; Editing by Anil D'Silva and Alexander Smith