UPDATE 2-U.S. sales boost Aviva Q1, help shares higher

(Writes through with shares, detail, analyst comment, quotes)

By Clara Ferreira-Marques

LONDON, April 24 (Reuters) - British insurer Aviva (AV.L) posted a 16 percent rise in life and pensions sales on Tuesday, boosted by U.S. business, with its newly acquired AmerUs unit making its first full quarter's contribution.

Britain's largest insurer said sales of life and pensions policies climbed to 7.75 billion pounds ($15.5 billion), a touch above an average forecast of 7.53 billion pounds from analysts.

Estimates from 16 analysts polled by the company had ranged from 6.82 billion to 8.11 billion pounds.

Aviva, which makes over 60 percent of its sales outside its home market and largely in continental Europe, said international life and pensions sales rose 25 percent.

In the UK, where growth across the sector has slowed from a bumper 2006, Aviva said sales ticked 3 percent higher.

"The outperformance came from their new acquisitions, rather than from organic growth. The organic growth looked pretty much in line," said analyst Peter Eliot at Man Securities.

Aviva's stock, which has underperformed the UK life sector by 6 percent and fallen 3 percent since the start of the year, was up 1.7 percent at 788-1/2 pence at 0826 GMT.