European stock markets struggled for direction on Thursday after preliminary euro-zone PMI confirmed business activity in the region continued to grow in May, while tensions heightened in Ukraine.

The Stoxx Europe 600 index was marginally higher at 340.49, but was swinging between small gains and losses.

Shares of SABMiller PLC gained 3.5% after the brewer reported a slight increase in full-year profit. The company said its strength in developing markets such as Africa and Latin America had held up in the past 12 months, but that it sees ongoing weakness in Europe and North America.

Also pushing higher, shares of Austria's third-largest bank in terms of assets, Raiffeisen Bank International AG , picked up 5.5% after the company reported an increase in first-quarter profit even though tensions between Ukraine and Russia caused an increase in risk provisions.

On a more downbeat note, shares of Royal Mail PLC slumped 7.5% after the company said it faces a couple of headwinds, including intense competition on the parcels side.

More broadly, investors took in a round of purchasing managers' indexes and the latest developments in Ukraine. At least 11 soldiers died and 30 others were wounded in an attack on troops in Ukraine's eastern region of Donetsk, according to media reports. The news came as Russia appeared to be pulling its troop back from the Ukraine border and Ukrainians prepare to head to the polls this weekend to pick a new president.

Meanwhile, Markit's euro-zone composite PMI fell to a two-month low of 53.9, from 54 in April. However, it came in slightly ahead of expectations and stayed above the 50.0 level that indicates growth. Markit said the data indicate the euro zone is having its best quarter in three years and that "ongoing improvement in business conditions was evident in both manufacturing and services."

The country-specific readings showed further divergence between powerhouse Germany and France, which has struggled with economic headwinds recently. The French composite PMI slipped into contraction at 49.3, while Germany stayed at 56.1 in May.

France's CAC 40 index fell 0.1% to 4,462.88, while Germany's DAX 30 index put on 0.1% to 9,711.88.

In China, the manufacturing PMI rose to a five-month high of 49.7 in May, from a final reading of 48.1 in April, according to the preliminary reading from HSBC. The data supported miners in Europe, as they are heavily exposed to Chinese growth. Shares of Antofagasta PLC picked up 2.1%, Rio Tinto PLC (RIO) rose 1.6% and Glencore PLC (GLCNF) added 1.1%.

The gains helped lift the U.K.'s FTSE 100 index , which rose 0.1% to 6,827.99.