Oct 16 (Reuters) - An Australian court on Wednesday

stopped U.S. drugmaker Cosette from abandoning its A$672 million

($437.6 million) takeover of Mayne Pharma ( MAYNF ), which now

awaits clearance from the Foreign Investment Review Board

(FIRB).

The ASX-listed pharmaceutical company said on Thursday it

would take all steps within its scope to implement the deal.

Shares in Mayne Pharma ( MAYNF ) jumped as much as 14.8% to A$6.5 at

open in Sydney, but were still trading way below the A$7.40

apiece that Cosette had offered.

Cosette has been trying to terminate its offer, after saying

in May that it was reviewing the deal because of a "material

adverse change" in Mayne's performance.

The stock had fallen to A$4.31 in its weakest trading

session since March 2009, when it disclosed Cosette's review of

the offer in late May.

The New Jersey-headquartered firm had flagged that there

have been a series of events, including Mayne's nine-month

trading update and the receipt and disclosure of a letter from

the U.S. Food and Drug Administration, which have caused Cosette

to form a view that a material change had occurred.

The Australian company rejected Cosette's termination

notice, arguing that no material adverse change occurred and

that the U.S. firm had no legal basis to abandon the deal.

The deal still requires the passing of certain conditions,

including approval by the FIRB and a greenlight at a second

court hearing at the Supreme Court of New South Wales.

The court hearing has been rescheduled to October 22.

The Australian Financial Review reported last month that the

South Australian government had asked FIRB to reject the deal.

Cosette did not immediately respond to a Reuters request for

comment.

($1 = 1.5356 Australian dollars)