* MSCI world index up 0.1% to record high
* Washington says trade deal done, China reticent
* Sterling heads for worst week since late 2017
* Graphic: World FX rates in 2019 tmsnrt.rs/2egbfVh (Updates prices throughout)
By Tom Wilson
LONDON, Dec 20 (Reuters) - World stocks touched record highs on Friday, as trading wound down before the year-end holidays, while the British pound was heading towards its worst week for more than two years amid renewed worries over how Britain will leave the European Union.
MSCI's world equity index, which tracks shares in 49 countries, gained a smidgeon to 561.31, bettering a record scaled on Thursday as optimism infused markets after the United States and China agreed an initial trade deal.
The MSCI index is on track to advance more than 1% this week, in what would be its fourth straight week of gains.
European shares led the way, with the broad Euro STOXX 600 gaining ground through the morning to add 0.6%. Indexes in Frankfurt, Paris and London all made similar gains in thin trading.
Yet Shell shares fell 1.1% after it said it expected impairment charges of up to $2.3 billion in the fourth quarter due to a weaker economic outlook.
On Wall Street, futures for the S&P 500 were flat near all-time highs, having risen more than 1% in the week.
Earlier, MSCI's broadest index of Asia-Pacific shares outside Japan added a sliver, having risen 1.2% so far this week and almost 5% this month.
Underscoring that the trade war issue has been put to bed for now, U.S. Treasury Secretary Steven Mnuchin said the United States and China would sign their so-called phase one trade pact in early January.
Mnuchin said the documentation was completely finished and just undergoing a technical "scrub", though Beijing has so far dodged all details of the deal.
The U.S. House of Representatives also overwhelmingly approved a new North American deal that leaves $1.2 trillion in annual U.S.-Mexico-Canada tradeflows largely intact.
Market players were already beginning to look at what the next steps for the Washington-Beijing saga will be in the new year.
"The focus will be on what the outlook is on a more comprehensive phase two deal - what the language is like, what Trump and the Chinese are saying about it," said Neil Wilson, chief markets analyst at Markets.com.
Wall Street investors had on Thursday pushed the S&P 500 to a sixth straight record, its longest such streak since January 2018. All three major U.S. indexes - S&P 500, Nasdaq and Dow - notched record closing highs.
Still, some data reminded investors of the fragile state of the world economy.
The mood among German consumers deteriorated unexpectedly heading into January, a survey showed, suggesting that household spending in Europe's largest economy could weaken at the beginning of next year.
On the currency front, sterling steadied after suffering a sharp reversal that left it facing its worst weekly fall since late 2017 of around 2%.
Former Bank of England deputy governor Andrew Bailey will be the central bank's next governor, Britain's finance minister said. Bailey will serve an eight-year term, with investors expecting continuity on monetary policy.
The pound was up 0.2% at $1.3029 having slipped overnight to below $1.30, a dramatic drop from a $1.3514 peak, after British Prime Minister Boris Johnson used his sweeping election victory to revive the risk of a hard Brexit.
"We see the biggest risks being to GBP/USD depreciation over the next two weeks as Brexit preparations take place amidst the most sluggish UK economy in 10 years," said Richard Grace, chief currency strategist at CBA.
The British parliament will vote at around 1430 GMT on Johnson's Brexit deal.
Against a basket of currencies, the dollar edged up 0.2% to 97.530 and was set for its best week in a month.
Traders were focused on a final reading of U.S. economic growth in the third quarter, due later in the session. (Reporting by Tom Wilson in LONDON; Editing by Alex Richardson)