(Adds no comment from Pfizer and AstraZeneca, context)
LONDON, April 20 (Reuters) - U.S. pharmaceutical giantPfizer has approached British rival AstraZeneca to propose a 60 billion pound ($101 billion) takeover, Britain'sSunday Times reported.
The paper cited senior investment bankers and industrysources saying that informal conversations about a deal hadtaken place between the two but that no talks were currentlyunder way after AstraZeneca resisted the approach.
Pfizer and AstraZeneca both declined to comment on thereport to Reuters.
AstraZeneca, Britain's second-biggest pharmaceuticals group,has been frequently touted as a potential takeover target as itwrestles with patents expiring on a number of best-sellingdrugs, leaving future growth uncertain.
Despite these problems, the company has attracted attentionfor experimental cancer drugs it is developing, which could beinteresting for Pfizer which has faced patent losses of its own,notably anti-cholesterol treatment Lipitor.
The two firms are familiar with each other's productsworking together on projects such as the pioneering of a newkind of clinical trial for cancer drugs announced last week.
Pfizer could use cash it has accumulated through overseassubsidiaries, which if repatriated to the U.S. would be heavilytaxed.
In the past Swiss drug firm Novartis and largerBritish peer GlaxoSmithKline have been mentioned aspotential suitors, although GSK has publicly said it is notinterested in making a large acquisition in recent years.
AstraZeneca, which announces first quarter results onThursday, has a market valuation of around $80 billion, comparedwith Pfizer - valued at $193 billion, according to ThomsonReuters data.
Earnings at AstraZeneca fell 6 percent in the fourth quarterof 2013, and the drugmaker has said it expects them to keepfalling in 2014 as generic competition to Nexium, its popularheartburn and ulcer drug, takes a big bite out of U.S. profitsfrom late May.
AstraZeneca has suffered a dry period in drug discovery inrecent years and badly needs to find new medicines to replaceblockbusters such as Nexium and Crestor, a treatment for highcholesterol that will lose patent protection in a few years.
Pfizer's last big acquisition was in 2009, when it boughtU.S. rival Wyeth for $68 billion.
($1 = 0.5949 British Pounds) (Reporting by Stephen Eisenhammer; additional reporting by BenHirschler; editing by Jane Baird and William Hardy)