LISBON, July 28 (Reuters) - Portugal's second-largest retailer Jeronimo Martins said on Wednesday its net profit jumped 85% in the second quarter, boosted by robust sales in its key Polish market and at home with the easing of coronavirus restrictions.

It said net profit rose to 129 million euros ($152.36 million) between April and June 2021, when Portugal and Poland started easing restrictions to control the pandemic, from 69 million euros a year ago.

Sales in the April-June period rose 11.2% compared to year earlier to 5.1 billion euros, driven by the sales of Polish food retail leader Biedronka, which increased 9.8% to around 3.6 billion euros, it said.

In Portugal, sales by the Pingo Doce supermarket chain rose also rose around 10% to 993 million euros.

Chief executive Pedro Soares dos Santos said in a statement the company's performance in the first half reflects the "strength and competitiveness" of its business models in all countries where it operates.

"The company showed it can maintain momentum and create differentiating commercial opportunities both in difficult times – such as earlier this year when a new wave of COVID-19 infections hit Poland – and in easier times, such as in the second quarter of this year," he said.

Earnings before interest, taxes, depreciation and amortisation (EBITDA) grew 4.7% to 513 million euros in the second quarter.

The company's total EBITDA margin, a key measure of profitability, edged up to 7.2% from 6.8% at the end of the first half and Biedronka's margin only slipped slightly to 8.9% from 9.0%.

It made investments worth 200 million euros, 60% in Poland, in the first half of the year, up from the 142 million euros invested in the same period last year.

"If restrictions implemented in our markets do not impact execution, the capex programme is expected to reach 700 million euros" this year, the company said. ($1 = 0.8467 euros) (Reporting by Sergio Goncalves; Editing by Catarina Demony and Sonya Hepinstall)