FILE PHOTO: The logo of AstraZeneca is seen on medication packages in a pharmacy in London, Britain April 28, 2014. REUTERS/Stefan Wermuth /File Photo

STOCKHOLM (Reuters) - British pharmaceuticals giant AstraZeneca AZN.L wants a transition period of at least three years when Britain leaves the European Union in 2019 and more clarity on what will happen in the longer term, its chairman said on Monday.

Uncertainty about what Britain’s relations with the EU will look like after March 2019 are hurting investment in the world’s fifth largest economy. Businesses most fear a situation where there is no deal at all.

AstraZeneca Chairman Leif Johansson said the firm wanted “at least three years” as a transition period, “and very early in that period, we need to know what to expect in years four, five and six,” he said told the Swedish daily Dagens Nyheter.

British Finance Minister Philip Hammond, speaking during the ruling Conservative Party’s annual conference, told BBC radio on Monday that uncertainty was hurting business confidence but said the government’s proposal for a two-year transition would help. [nS8N1JA01C]

Foreign Secretary Boris Johnson has said the transition period must not last more than two years.

Johansson said AstraZeneca, created from a merger between Sweden’s Astra and Britain’s Zeneca in 1999, did not expect a “cliff-edge” exit without a deal but said it remained a risk.

“There is a logic among the political leadership that you just don’t back down until the last minute.” he said. “Then, finally, after pulling an all-nighter, you get to a result.”

AstraZeneca was preparing for a situation where there was no deal but did not yet have concrete plans, Johansson said.