SAN FRANCISCO — Twitter said Thursday that the number of active monthly users has soared to more than 100 million with the majority of people logging in on the go.

"We're seeing tremendous growth on mobile," Twitter chief executive Dick Costolo said during an informal 'state of the union' update with reporters at the microblogging service's headquarters in San Francisco.

The number of "global active users" has jumped more than 80 percent from the start of the year with mobile climbing 40 percent each quarter for the past year, according to Costolo.

More than 400 million people monthly visit the website as compared with 250 million at the start of the year, according to figures he provided from a Google analytics service.

"There are still a lot of people who don't log into Twitter but use Twitter every day," Costolo said. "They come and search or read pages."