Stronger pound drags FTSE 100 lower as virus worries remain

(Corrects milestone in first paragraph to April, not June; Adds dropped letter in headline)

* Galliford surges on return to profitability forecast

* Whitbread jumps on Barclays' upgrade to 'overweight'

* FTSE 100 down 0.1%, FTSE 250 up 0.1%

Nov 13 (Reuters) - London's FTSE 100 retreated on Friday as concerns over rising COVID-19 infections hit mining stocks and a stronger pound pressured exporters, although the index looked set to post its best weekly gain since April on hopes of an effective vaccine.

The commodity-heavy index fell 0.1%, with energy and mining tracking lower oil and metal prices.

A stronger pound also weighed on dollar earners such as British American Tobacco Plc, Experian Plc, Diageo Plc and Unilever Plc.

The domestically-focussed mid-cap FTSE 250 index added 0.1%.

Both indexes are set for their second straight weekly gains, aided by new local stimulus measures and as U.S. drugmaker Pfizer Inc said on Monday its COVID-19 vaccine was 90% effective.

"Markets have just run out of steam as we're now out of the initial hubbub of the U.S. election and on the other side of this vaccine news," said Connor Campbell, a financial analyst at Spreadex in London.

U.S. President-elect Joe Biden cemented his electoral victory by capturing the battleground state of Arizona late on Thursday, but the transition to his administration remains in political stasis as President Donald Trump refuses to accept defeat.

Meanwhile, a day after UK reported 33,470 new cases of COVID-19, its highest daily total to date, British transport minister said he would be making an announcement on changes to the country's 14-day quarantine rule for travellers "very soon".

In company news, Premier Inn-owner Whitbread Plc rose 1.1% after Barclays upgraded the stock to "overweight", while Rolls-Royce jumped 5.6% after JP Morgan raised its target price on the stock.

Construction firm Galliford Try Holdings Plc surged 15.3% after forecasting a return to profitability in the first half of this financial year. (Reporting by Devik Jain in Bengaluru; editing by Uttaresh.V and Subhranshu Sahu)