O2 and its sister firm Be Broadband saw a slight drop in internet subscriptions during the second quarter of the year, it has been reported.
The broadband providers, which are owned by telecoms giant Telefonica, shed a combined 16,300 customers between April and June 2011.
In total, the firms now have 652,900 broadband deal subscribers, down from 669,200 in the first quarter of the year.
Since the firms lost just 2,400 customers between Q4 2010 and Q1 2011, the rate of decline accelerated during the last three months.
Yet Telefonica UK managed to increase its revenues by 0.9 per cent on a like-for-like basis during the quarter, as takings rose to £3.1 billion.
"In the first half of the year, [we] performed well in an increasingly complex economic and competitive environment," the organisation stated.
O2 and Be Broadband are not the only broadband providers with cause for concern this summer.
Rival broadband providers Virgin Media and TalkTalk also saw a drop in broadband customers during the second quarter, as BT and Sky expanded their user bases.