IDG News Service — Twitter's mobile user base has spiked 62 percent since mid-April, thanks in great part to the release of official Twitter applications for iPhone, Android and BlackBerry phones.

During this timeframe, the proportion of Twitter users who sign up for the service directly from a mobile device has increase to 16 percent, up from five percent, Twitter CEO Evan Williams said in a blog post on Thursday.

"As we had hoped in April, these clients are bringing more people into Twitter, and, even better, they are attracting and retaining active users. Indeed, 46 percent of active users make mobile a regular part of their Twitter experience," Williams wrote.

Prior to the release of those official mobile applications, mobile adoption of Twitter had been held back by the "plethora" of mobile applications that weren't specifically endorsed by the company, which confused people while trying to pick one, he wrote.

Still, the most popular way of accessing Twitter from a mobile device remains the company's mobile site, used by 14 percent of all Twitter users. SMS service and the Twitter for iPhone application each have 8 percent of unique users, followed by the Twitter for BlackBerry application with 7 percent.

Williams also said that externally-built Twitter applications have increased to almost 300,000, almost tripling since the company held its Chirp developer conference in mid-April. Meanwhile, registered users are at 145 million people.