PayPal suffered an outage last week, which prevented most members from using the online payment service to conduct transactions.

The technical problems began at about 11am US Eastern Time (3pm UK time) and were prematurely declared solved around 1pm (5pm), although issues lasted until about 3:30pm(7:30pm).

Outages and availability problems with online payment systems such as PayPal inevitably cost merchants money in lost sales, dissatisfied customers and tarnished brands.

In its blog postings about the issue, PayPal hasn't given a reason for the outage but said it plans eventually to provide details about what went wrong. "I'd like to apologise on behalf of the company to anyone who was affected," wrote a PayPal official identified only as Anuj.

PayPal, with more than 87 million active PayPal accounts - and growing - in 190 markets and 24 currencies worldwide, is increasingly important to the financial health of parent company eBay.

Last week, parent company eBay reported PayPal's third quarter revenue was up 22 percent rom a year earlier, to $838m.

Revenue for all of eBay increased just one percent, eBay said last week. PayPal made up 37 percent of eBay's overall revenue, up from 31 percent in 2009's third quarter.

See also: 9 alternatives to Paypal