Visto, the Silicon Valley push email developer, told London staff on Thursday that about one third are for the chop, because financial backers are demanding a profit this year.

The London round of cuts is described by sources as "large scale", affecting senior IT staff, development, product services and pre-sales workers. A Visto US representative today confirmed "limited lay-offs" worldwide, but declined to talk numbers or locations.

Sources say the Redwood City-based firm is under big pressure to start bringing returns on the $300m-plus venture funding sunk over several rounds into the company, which was set up in 1996. The privately-held firm has announced its intention to IPO four times in four years.

"I guess our share options won't be worth much now either, huh," said one source. "We're all on the job hunt here - never seen so many job website pages open in one place before."

In recent years Visto has launched a series of patent litigations against RIM, Microsoft, Seven Networks, and Good Technology. ®

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• Visto makes Good (24 February 2009)
• Belts tightened in push email (17 October 2008)
• Visto razzes RIM with NTP alliance (15 December 2005)