San Francisco, California based social networking and micro-blogging service, Twitter Inc. is reportedly raising cash from one or more unnamed venture capital firms, which have valued the Twitter's business at nearly $250 million.

One of the reliable online tech sources has reported that Twitter has got nod for the cash, from the venture capital firms that have valued it as $250 million business.

According to the reports, Twitter, which turned down a $500 million acquisition offer from Facebook, is currently growing in its value and web traffic.

Twitter is getting more visits than Facebook, say some studies of online "market share". According to ComScore study, "Twitter's traffic flow increased five times, to 5.57 million, year over year as of September".