Stocks wobbled Thursday as traders looked to a major central bankers' meeting and weighed comments by US President Donald Trump about the debt ceiling.

European indices ended mixed, with London's benchmark FTSE 100 index rising 0.3 percent as traders reacted to official data confirming Britain's economy grew 0.3 in the second quarter despite high inflation and uncertainty over Brexit.

US stocks were choppy throughout the session, but ended modestly lower amid lingering uncertainty about Washington after Trump again took to Twitter to castigate Republican leaders. Retailers such as Wal-Mart Stores and Target fell after Amazon said it intends to cut prices at its Whole Foods acquisition, signaling a possible price war among grocers.

Analysts pointed to unease over Friday's central bank summit in Jackson Hole, Wyoming that could signal a more dramatic shift away from the easy money policies of recent years.

At the same time, analysts are watching to see if Federal Reserve Chair Janet Yellen emphasizes low inflation, which would be seen as a signal the Federal Reserve could abandon plans for a third interest rate hike after two earlier rises.

ECB officials have also highlighted the higher euro currency as a concern, a point that could affect plans to unwind its stimulus program.

"Investors hesitated to move the market ahead of comments from the world's two most influential central bankers -- Fed Chair Janet Yellen and European Central Bank President Mario Draghi," said a note from Briefing.com.

Questions about Trump also remained in focus after the US president accused Republican leaders of foot-dragging on his priorities ahead of an end-September deadline for Congress to fund the government into 2018 and raise the legal cap on federal borrowing in order to avoid a debt default.

Trump tweeted angrily against Senate Republican leader Mitch McConnell and Paul Ryan, the speaker of the House of Representatives, after on Tuesday threatening a government shutdown if Congress does not fund his border wall with Mexico.

"While Mr Trump is talking tough about a government shutdown, traders will be fearful of going long," said analyst David Madden at CMC Markets UK.

US retailers took a hit after Amazon vowed to cut prices at Whole Foods once the acquisition closes on Monday.

Shares of Wal-Mart sank 2.0 percent, while Costco Wholesale shed 5.0 percent and Target 4.0 percent after Amazon announced it would immediately cut prices on select products to make natural and organic food "affordable for everyone."

"Amazon is wasting no time in making the most of its newest division," said a note from Neil Saunders at GlobalData Retail. "Worryingly for others in the market, these things are only the opening salvo in what will be a time of rapid change."

- Key figures around 2100 GMT -

New York - Dow: DOWN 0.1 percent at 21,783.40 (close)

New York - S&P 500: DOWN 0.2 percent at 2,438.97 (close)

New York - Nasdaq: DOWN 0.1 percent at 6,271.33 (close)

London - FTSE 100: UP 0.3 percent at 7,407.06 points (close)

Frankfurt - DAX 30: UP 0.1 percent at 12,180.83 (close)

Paris - CAC 40: DOWN less than 0.1 percent at 5,113.13 (close)

EURO STOXX 50: UP 0.3 percent at 3,447.81

Tokyo - Nikkei 225: DOWN 0.4 percent at 19,353.77 (close)

Hong Kong - Hang Seng: UP 0.4 percent at 27,518.60 (close)

Shanghai - Composite: DOWN 0.5 percent at 3,271.51 (close)

Euro/dollar: DOWN at $1.1800 from $1.1806 at 2100 GMT

Pound/dollar: UP at $1.2799 from $1.2798

Dollar/yen: UP at 109.26 yen from 109.05 yen

Oil - Brent North Sea: DOWN 53 cents at $52.03 per barrel

Oil - West Texas Intermediate: DOWN 98 cents at $47.43

source: AFP