European markets opened higher on Wednesday and immediately reversed early gains over the increasing possibility of US military intervention in Syria.

The Stoxx Europe 600 index opened 0.2% higher to 302.45.

Britain's FTSE 100 opened 0.1% higher.

Germany's DAX 30 opened 0.2% higher.

France's CAC 40 index opened 0.3% higher.

Italy's FTSE MIB was down 0.22% in early trade.

Spain's IBEX 35 was down 0.23% in early trade.

President Barack Obama has gained the support of key US senators for a military strike against Syrian President Bashar al-Assad's regime.

Republican and Democratic senators have concurred on a draft resolution pushing for military action. "I believe that my colleagues should support this call for action," John Boehner, Republican speaker of the House of Representatives, told reporters following the hearing. The draft prohibits the use of ground forces and limits the intervention to 60 days.

The proposal will be put to vote next week when Congress reconvenes.

Market participants expect that debates over Syria, and not economic reconstruction or central bank policies, could top the agenda at this week's G20 summit in Russia.

Heads of the Brics governments are expected to discuss the issues surrounding the formation of a Brics development bank when they meet at the G20 summit in St Petersburg on 5-6 September.

G20 leaders are also expected to discuss the repercussions of tight central bank monetary policy on emerging market economies at the summit.

Market participants in Europe will be tracking eurozone-wide second quarter GDP data alongside retail sales data for the month of July, due out today. They will also be tracking UK and eurozone services PMI data for the month of August.

Data from the UK showed that overall shop prices declined for the fourth consecutive month in August as prices in non-food categories fell to their lowest level since December 2008 amid widespread discounts and promotions from retailers.

The British Retail Consortium (BRC) said that shop price deflation came in at an annual rate of 0.5% in August, the same as in July.

In Asia and the US

In Asia, the Japanese Nikkei finished 0.54% higher on Wednesday. Australia's S&P/ASX closed 0.67% lower while South Korea's Kospi ended 0.04% lower.

Earlier in Asia, markets were mixed as market participants took profits, following strong gains earlier this week, just as the prospect of US military action in Syria pulled down the overall sentiment in the region.

Australia's economy grew by 0.6% in the April to June quarter, according to the Australian Bureau of Statistics. Analysts had expected a 0.5% economic growth rate for the three months to June.

Australians will elect a new government later this week.

On Wall Street, indices ended higher however concerns surrounding US action in Syria capped gains.

The Dow finished 23.65 points higher at 14,833.96. The S&P 500 closed 6.80 points higher at 1,639.77 while the Nasdaq ended 22.74 points higher at 3,612.61.