A man walks past an O2 phone store in Manchester, Britain March 7, 2016. REUTERS/Phil Noble/File Photo

LONDON (Reuters) - Britain’s O2 said it will allow customers to choose how much they pay upfront for a smartphone and how they spread the payments of the balance, targeting subscribers who want more control over their mobile contracts.

The operator, owned by Spain Telefonica TEF.MC, said customers would be able to pay for their new devices in monthly increments for any period between three and 36 months, all with no interest charged, as well as choosing an airtime plan.

Chief Executive Mark Evans said on Wednesday: “Our custom plans put power back in the hands of the consumers who don’t want to be tied down by rigid contracts especially at a time when certainty and transparency are at a premium in today’s economic environment.”

O2, the second largest British operator after BT BT.L, said the "Custom Plans" built on the tariffs it introduced in 2013 that separate the cost of airtime and the cost of paying for the phone, and the change it made last year that allows customers to increase or decrease their airtime each month depending on their data needs.