Nokia may have moved to Windows, but it is still trying to woo the developers working on its old platform, Symbian, sending an open letter emphasizing that the company is not abandoning the platform.

Symbian is one of the most popular platforms in the world, because Nokia's phones are the most ubiquitous. But in February the company announced it was moving to Windows Phone 7 as its primary platform, thought the first phones would not be hitting the shelves until 2012.

That announcement, predictably, made many wonder if it was worth staying in the Symbian development business. On its blog, Nokia's vice president of Forum Nokia and developer community, Purnima Kochikar, said Nokia will keep supporting Symbian in an open letter to Symbian developers.

We're making investments that will help us to engage and attract existing and new Symbian users and allow us to launch new competitive smartphones, she wrote in the letter. Kochikar said the company plans to issue Symbian updates in the summer.

Kochikar avoided a fixed timetable for Symbian support. I've been asked many times how long we will support Symbian and I'm sure for many of you it feels we have been avoiding the question. The truth is, it is very difficult to provide a single answer. We hope to bring devices based on Windows Phone to market as quickly as possible, but Windows Phone will not have all language and all localization capabilities from day one.

She also noted that Nokia has a legal obligation to continue Symbian support in some countries. But the thrust of Nokia's strategy will still be to encourage users to switch to Windows Phone 7 devices as they replace their phones.

The development platform, called Qt, for Symbian will also be used for future MeeGo technology, and Kochikar said Nokia is committed to it.

On the blog itself, comments were a mixed bag at best. One, with the handle patrick.regnouf called it Such a nice way to tell us that Symbian is deader than dead! Another, mikesuh agreed that leaving the Symbian platform was a bad decision. He noted that Nokia spent years developing Qt, and that as a development platform it was a good tool for developers.

What's worse is that development for the WP7 is possible only by using Windows and MicroSoft tools. I am a long time Linux user and it's great that developemtn [sic] of Qt apps for the Symbian is possible on Linux too, mikesuh wrote.

When the partnership with Microsoft was announced, Nokia CEO Stephen Elop said it was necessary for Nokia to be part of an ecosystem that could be rolled out quickly. A MeeGo device has yet to ship and the Symbian-based app store, Ovi, had not grown the way the iOS or Android app markets did.

Apple's App Store and the Android Market both have in the hundreds of thousands of apps, whereas Nokia's Ovi had about 30,000 at the end of 2010.

Even though Nokia is one of the best-selling phone brands, the company has come under increasing pressure in the low-priced mobile market from Chinese and Korean competitors. Nokia has yet to roll out a smartphone that has gained the buzz of the iPhone and hasn't got a tablet strategy.

Elop noted that the North American market is critical to Nokia's future success, and that by offering a Windows-based device it can make inroads there, where the Finnish company has been weak.