* News Corp unit plans to appeal
* Valassis has two other lawsuits pending against unit
* Valassis shares up 45 pct in afternoon trade
NEW YORK, July 23 (Reuters) - A Michigan court judge awarded Valassis Communications Inc VCI.N $300 million in damages in a lawsuit that it filed against a News Corp (NWSA.O) subsidiary, the newspaper coupon company said on Thursday.
Valassis shares jumped as much as 64 percent in morning trading before paring their gains to be 45 percent higher in Thursday afternoon trade.
Valassis in its lawsuit claimed that News America Marketing engaged in unfair competition and "tortious interference," the company said in a statement on Thursday.
A jury in the Wayne County Circuit Court in Michigan found News America Marketing liable for both counts, Valassis said.
News America Marketing will appeal the decision, said Chris Mixson, the company's president.
"We are disappointed with today's decision, which rewards a company that turned to litigation as its business strategy rather than compete," Mixson said.
Mixson said the jury was "hampered" by the court's decision to not allow News America to introduce to the court a Federal Trade Commission analysis that Valassis "had made 'an effort to induce collusion' when it announced a new pricing policy in a conference call with investors.
"This information would have shown that this lawsuit was merely part of a larger strategy to get News America Marketing to raise its prices, a move that would have affected both our clients and their consumers by reducing the number of coupons available -- a consequence that would be extremely unfortunate in this economy," Mixson said.
Valassis also has lawsuits pending against the News Corp unit in a federal court in the eastern district of Michigan and the California Supreme Court in Los Angeles.
Valassis shares were up $3.17 to $10.20 on the New York Stock Exchange. News Corp shares were up 3.1 percent, at $9.97 on the Nasdaq stock market. (Reporting by Robert MacMillan; Editing by Tim Dobbyn)