International property investment firm CLS has hailed a robust start to the year after profits jumped by a third in the first half.The firm, which manages office properties in London, France, Germany and Sweden, said profit before tax was up 32% to £37.1m, with earnings per share up 35% to 69.9p.In the six months to 30 June 2011, its property portfolio gained 4.5% to £924.8m on a like-for-like basis, of which 2.9% was due to currency movements.Vacancy rates fell slightly across the portfolio to 4.2%, down from 4.3% at the end of December.The firm now intends to return £4.4m to shareholders in September by means of a buy-back of 1 in 72 shares at 700 pence per share.This follows a £7.1m buy-back scheme in April.Sten Mortstedt, executive chairman of CLS, said the firm was benefitting from investment across four European property markets, three currencies, and a broad and growing range of funding structures and lending sources."There has been an acceleration of attractive opportunities coming onto the market in each of our geographical areas; we are actively pursuing a number of these and expect to be able to announce further acquisitions over the next six months," he said.CLS' shares went up 8% following the announcement.