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Twitter Inc., the social-networking service that lets users share 140-character messages, said it�s looking into an increase in error rates that�s making it harder to access the site.

�We are aware of the problem and taking action,� the San Francisco-based company said today at about 3 p.m. New York time on a blog devoted to the site�s status.

Twitter has struggled with service disruptions as its traffic surges. The average number of postings sent daily rose to about 140 million in the past month, up from 50 million a year earlier, the company said this week. Twitter had reported �elevated error rates� an additional four times in February, along with a range of other difficulties.

The company is increasingly counting on its site to deliver advertising, potentially putting more revenue at stake when the service goes down. Twitter�s surging prospects and potential ad revenue have helped drive up its valuation. It was valued at $3.7 billion in December when it received an investment led by venture-capital firm Kleiner Perkins Caufield & Byers. That compares with $1 billion in September 2009, according to a person familiar with the matter.

(Source: Bloomberg)