Facebook has agreed to buy start-up app-maker Onavo, the Israeli company said on its website on Monday, without giving any details of the deal.

Facebook is paying between $150 million and $200 million, the Calcalist financial news website said, making it the social media company's biggest acquisition in Israel.

The company, founded three years ago, said that once the transaction closes, Onavo's mobile utility application - which helps people cut mobile phone costs through more efficient use of data - will run as a standalone brand.

Onavo has raised $13 million in venture capital, according to Calcalist. Its investors include Sequoia Capital and Motorola Mobility Ventures.

Onavo will keep its Israeli offices, according to the Haaretz news website.