* To use 300 million pounds to pay off debt
* Sees automotive segment improving in second half
* Sales in 5 months down 32 pct excluding currency, Filton
* Shares down 1 pct
* Pali upgrades to "buy" from "sell" (Adds CEO, analyst comments, share price)
By Ben Deighton
LONDON, June 18 (Reuters) - British engineer GKN said on Thursday it is hoping to pay 300 million pounds off its debt after raising 423 million pounds ($688 million) through a fully underwritten rights issue.
The plane and car engineer is issuing the shares at 50 pence per share, representing a 58 percent discount to Thursday's close of 119 pence. As at 31 May 2009, the Group's net debt was 928 million pounds.
GKN also announced a further 900 job cuts on Thursday as sales in the first five months of the year fell by 32 percent on a constant currency basis, discounting the contribution of Filton, the manufacturing operation it bought from Airbus in September last year.
However, the company has earmarked some of the 100 million pounds of the cash raised to fund expansion.
Chief Executive Kevin Smith told reporters on a conference call that he was expecting an improvement in its leading automotive business in the second half of the year.
"Our customers are all going through significant inventory reduction we feel that is starting to bottom out ... we are reasonably optimistic of some improvements through the second half," he said.
"Our customers are concerned about security of supply in terms of their existing business and also in the way that they source new business ... we've had discussions with them on both of those fronts."
The rights issue announcement prompted broker Pali to upgrade its stance on the stock to "buy" from "sell", and by 1046 GMT shares had pared losses, coming off lows of 100 pence to be down just over 1 percent at 117 pence.
Pali analyst Sanjay Jha likened it to the rights issue by industrial materials firm Cookson in January, which saw shares fall by as much as 48 percent before ending up 12 percent.
Pub group Marstons also announced a 176 million pounds rights issue on Thursday to fund growth, while Punch Taverns earlier this week unveiled a 375 million pound share issue to trim its 4.2 billion pound debt.
GKN's six-for-five rights issue is fully underwritten by J.P. Morgan Securities, UBS Investment Bank, HSBC Bank and RBS Hoare Govett. (Editing by Mark Potter and Rupert Winchester) ($1 = 0.6149 pound)