Allergan has confirmed it has held preliminary talks about a takeover by pharmaceutical giant Pfizer.

The Dublin-based Botox-maker said no agreement had been reached and there was “no certainty that these discussions will lead to a transaction”.

Allergan shares were up more than 6% on October 29 trading in New York.

Analysts said Pfizer needed to boost profits and may be looking to escape relatively high US corporate tax rates by moving its headquarters to Dublin.

“Allergan today confirmed that it has been approached by Pfizer Inc. and is in preliminary friendly discussions regarding a potential business combination transaction,” the company said in a statement.

“The company will not comment on speculation regarding the terms of a potential transaction.”

The talks were first reported in the media on October 28.

In 2014, Pfizer made an offer to buy another UK drugs group, AstraZeneca, but Astra rejected the offer, arguing it undervalued the company.