London: Twitter has been in talks with Facebook about inter-operating their services, after Facebook blocked Twitter integration a move that Twitter co-founder Evan Williams described as "frustrating" at the Web 2.0 conference in San Francisco.

"We're talking to them often to see if there is a way to work together, but so far neither side has found out a way to do that," Williams said.

He also admitted that the company had "screwed up" its relationship with third-party developers, who have complained about the way that its product development has begun to encroach on territories that they thought they had sewn up for themselves.

Twitter originally set up an API to let third-party companies hook into its system because "we thought it would be neat", Williams told the Web 2.0 conference, but as it grew it realised it needed to fill in holes in its feature set —leading to the acquisition of the Twitter client Tweetie, and previously the Twitter search company Summize.

"We've learned a lot about having an ecosystem and working with third-party developers and we've screwed up a lot of that," he said.

But he said the company will keep on adding facilities whether or not other companies were already offering them. It launched an analytics service on Wednesday — stepping on the toes of other companies which offer similar functions.

"We launched Twitter sort of as a Model T — it was very basic, but was popular, and it got people excited, and a swarm of developers came in and made it better in the after-market, and that was great [because] it increased demand for the Model T and we could focus on increasing production but gradually we realised that wasn't really serving users as much as we should," he said. Williams, who recently stepped aside as chief executive, said his company was not running low on capital, amid media reports that the company is considering raising a large round of funding.

Williams told the Web 2.0 conference in San Francisco that Twitter has "a lot of money in the bank", but wouldn't comment on whether the company was talking to investment firms about funding.

The company has around 175 million users but has only recently started efforts to generate revenue through special ads that appear in certain parts of its service.

Williams said the company's initial efforts at generating advertising revenue had exceeded the company's expectations though he wouldn't say how much it had garnered. He did say that most of the advertisers who have tried its "promoted tweets" and "promoted trends" services have returned to use them.

Funding forecast

TechCrunch suggested on Wednesday that Twitter is looking for more than $100 million in funding, having already raised more than $160 million, and that it would be valued at about $3 billion — suggesting the company would look to sell around 3 per cent of its stock in the round.

Likely investors would include Russian investment firm DST Global, which has previously invested in Facebook, Zynga and the coupon company Groupon. Twitter declined to comment on the rumours. Its last funding round of $100 million valued the company at $1 billion, indicating that it sold about 10 per cent of its stock there.

At Web 2.0 the DST Chairman Yuri Milner acknowledged that Twitter was among the 25 to 30 companies that would fit his firm's investing strategy during an on-stage interview, though he declined to comment specifically on whether DST was talking to Twitter about a deal.

Milner said that DST invests in companies that typically have a $1 billion plus valuation, are in the "social internet space," and can be located anywhere in the world.