* FTSE 100 down 0.1 percent
* GlaxoSmithKline profits at expense of AstraZeneca
* Whitbread slides; Shell, WPP among gainers
* Market eyes U.S. data in afternoon session
By Simon Jessop
LONDON, April 28 (Reuters) - Britain's top shares were slightly lower after a mixed bag of updates from firms such as Royal Dutch Shell and AstraZeneca, and volumes were expected to remain weak into the four-day holiday weekend.
At 1119 GMT, the FTSE 100 was down 0.1 percent at 6,060.00 points after paring early gains, with volumes around a quarter of their 30-day daily average half way through the session on the last trading day of the month.
Direction as the market heads into the afternoon session is seen coming from the United States, where GDP and jobless data is due to be released, all of which will give further clues to the strength of recovery in the world's largest economy.
"Lots of corporates are scheduled to report Q1 earnings before the market open with the highlights being Coca Cola, Time Warner and Tyco International," Andrew Sykes, trader at Spreadex, said, with "the big one", Microsoft, due after the market closes.
Among the heavyweight UK fallers in relatively heavy volume was drugmaker AstraZeneca, down 2.5 percent after posting forecast-lagging results that in turn profited peer GlaxoSmithKline, up 2 percent.
"Investors looking over the first quarter results from GlaxoSmithKline, yesterday, and AstraZeneca this morning have two very different businesses to consider - nevertheless, we believe the choice between the two is straightforward, and can be summarised in two words: BUY Glaxo," Seymour Pierce said in a note.
Also on the upside, miners reversed several days of falls after metals prices got a weaker-dollar boost from dovish comments on monetary policy overnight from U.S. Federal Reserve chairman Ben Bernanke.
"With the prospect of ultra-easy monetary policy continuing for the foreseeable future in the world's largest economy, traders are feeling more confident about holding the bullish view and risk appetite is expected to be high," said Jonathan Sudaria, night dealer at London Capital Group.
Elsewhere among corporate earnings on Thursday, Royal Dutch Shell rose around 0.7 percent, bucking a weaker sector index, after the oil major posted forecast-beating results on oil price and refining margin gains.
Global advertising group WPP was also among the gainers, up 2.5 percent after it raised its outlook for the year, while insurer Standard Life led the market thanks to forecast-beating sales.
Kevin Arenson, chief investment officer at fund-of-hedge-fund investor Stenham Advisors, who oversees $3.5 billion in assets, said he remained "neutral to slightly positive" on UK equities.
Most of that optimism came from the large amount of earnings made by UK corporates outside of the UK, especially in light of any weakening in Sterling going forward.
WHITBREAD STUMBLES
Underpinning some of the weaker corporate updates was the fragile outlook for UK consumers, a view underlined by the overnight release of fresh consumer morale data.
The GfK NOP consumer confidence index fell to -31 in April from -28 in March, its lowest since February 2009 and against expectations for a steady reading.
Against that backdrop, hotel operator Whitbread fell 4.5 percent in heavy volume to lead the FTSE fallers, weighed down by downbeat comment on the outlook from its chief executive after forecast-beating results.
While the potential weakness of the UK consumer environment was "clearly a headwind", Peter Sullivan, HSBC head of equity strategy for Europe and the U.S, said, equities remained broadly attractive.
"Equity multiples are low, real interest rates are very low and likely to remain so for some time, and the global economy is recovering," he said.
"It's tough to be too negative on equities when you've got those three conditions." (Editing by Jon Loades-Carter)