UPDATE 2-UK shares weaken, Tullow loses half its market cap

* FTSE 100, FTSE 250 down 0.1%

* Tesco outshines the main index

* Some domestic stocks gain on election optimism

* Tullow Oil plummets after co cancels dividend, CEO exits
(Adds company news items, updates share moves)

By Muvija M and Shashwat Awasthi

Dec 9 (Reuters) - London's exporter-heavy FTSE 100 inched
lower on Monday as oil majors and Asia-exposed financials fell
on China growth worries and as the pound strengthened, while a
72% slump in Tullow Oil single-handedly dragged down midcaps.

The blue-chip index was gave up 0.1%, with its
dollar earners including spirits company Diageo and
pharmaceutical giant AstraZeneca taking a hit from gains
in sterling ahead of UK general election later this week.

The FTSE 250 midcap index was also down by the same
level, with Tullow Oil recording its steepest one-day
fall since early 2004 after the oil and gas explorer scrapped
dividend and announced the exit of its CEO.

Monday's drop wiped off roughly half of Tullow's market cap,
or 1 billion pounds ($1.28 billion), as the stock tumbled to its
lowest in 15-1/2 years. Rival Premier Oil also fell 8%.

Other news-related moves saw Tesco top the bluechip
index with a 5% rise after the retailer started a review of its
operations in Thailand and Malaysia.

Helping limit losses on the midcap bourse was engineering
firm Senior Plc, which jumped 7% on news that it was
reviewing options for its aerostructures business. Marks &
Spencer added 3.5% after a double upgrade from Goldman
Sachs.

Elsewhere, China's exports in November shrank for the fourth
consecutive month, fanning worries over the impact of the
Sino-U.S. trade war on the world's second-largest economy and
overshadowing Friday's strong U.S. jobs data.

"The contrasting U.S. and Chinese data should swing the
trade negotiation pendulum back to neutral from the Chinese side
amongst the world's trade watchers," OANDA analyst Jeffrey
Halley said.

Investors were also trying to size up the chances of a new
round of U.S. tariffs on $156 billion worth of Chinese goods
from Dec. 15.

While signs of progress in the trade negotiations lifted the
FTSE 100 to its biggest one-day gain since July on Friday, the
bourse still marked its steepest weekly fall after contradictory
messages from U.S. President Donald Trump earlier on.

"More soothing noises on the negotiations emerged from
Washington D.C. on Friday, but one gets the sense that this
Sunday's next round of tariffs on China is no longer the line in
the sand it once was perceived to be," Halley said.

On Monday, some of Britain's more domestically-exposed firms
such as Lloyds and Barclays outperformed as
investors bet on the Boris Johnson-led Conservatives to win the
election this week and deliver Brexit.

"Three days to polling day and the polls are looking good
for Boris Johnson..., although the spectre of tactical voting
still lingers," Raymond James analyst Chris Bailey said.

($1 = 0.7794 pounds)

(Reporting by Muvija M and Shashwat Awasthi in Bengaluru with
additional reporting by Tanishaa Nadkar; Editing by Arun Koyyur
and Mark Heinrich)