UPDATE 3-Premier Oil plans rights issue for buying spree towards 100,000 bpd

* Premier to buy BP assets, increase Tolmount stake

* Plans $500 mln rights issue

* Sees FCF of $1 bln from acquisitions to end 2023

* Extends debt maturity to 2023

* Premier, Rockhopper find partner for Sea Lion project
(Adds Premier comment on debt holders, background)

By Shadia Nasralla

LONDON, Jan 7 (Reuters) - Premier Oil is set to buy
stakes in North Sea oilfields Andrew and Shearwater from BP
for $625 million and increase its stake in the Tolmount
gas project in a deal with Dana worth $191 million, it said on
Tuesday.

Premier said the deals would generate more than $1 billion
in free cash flow by the end of 2023, push its output above
100,000 barrels of oil equivalent per day by next year and add
82 million barrels of reserves and resources to its portfolio.

The acquisitions, the latest in a string of deals moving
North Sea assets from oil majors to smaller groups, would be
funded by a $500 million equity raise "which has been fully
underwritten on a standby basis", existing cash and, if needed,
a loan of $300 million.

Premier's shares shot up around 13% to their highest in over
a year by 0858 GMT.

Premier had also announced an extension of its debt maturity
timeline by over two years to the end of November 2023. Premier,
which had a market capitalisation of around $1.1 billion before
the announcements, has a debt pile of around $2 billion.

Chief Executive Tony Durrant told Reuters the response from
major shareholders for the plans was "extremely positive"
although hedge fund and Premier bond holder ARCM said it would
fight the plans.

Premier said it was confident it had enough support from its
other creditors to get permission for the transactions at a
so-called at the Scheme of Arrangement Court meeting.

The group said it expected to confirm details of the issue
in the first quarter.

ARCM, which has had a growing short position in Premier
shares since 2017 reaching around 17% of the oil group's stock,
around four times higher than the average for London-listed
firms, objected to the plans.

ARCM, also describing itself as Premier's largest creditor
at 15% of its debt instruments, said it would "take all steps"
to oppose the deals, objecting to Premier's focus on North Sea
gas assets amid strong Russian and U.S. gas imports.

In a string of announcements on Tuesday, Premier's partner
in the Sea Lion project off the Falklands Islands, Rockhopper
, said they had signed a preliminary deal for Navitas
Petroleum LP to buy a 30% stake.

The new partnership will reduce Premier's obligations to
build Sea Lion to around $285 million from $500 million, Durrant
said.

"Today's announcements have the potential to transform it
into one of the more investible names in the space," said BMO
analyst David Round.

"Not only will these deals add scale and growth, but
importantly Premier's deleveraging will accelerate towards much
more manageable levels."

(Reporting by Shadia Nasralla; editing by Jason Neely)