(Reuters) - Credit data company Experian Plc (>> Experian plc) said it had received a number of class actions related to the theft of T-Mobile US Inc (>> T-Mobile Us Inc) customer data at its server and was working with U.S. and other law enforcement agencies to investigate the matter.

Experian also said on Tuesday it raised its $600 million share buyback programme by $200 million using proceeds from recent divestments.

The company, which is best known for running consumer credit checks for banks, landlords and retailers, said it would pay an interim dividend of 12.5 cents per share.

The FTSE-100 stock rose as much as 6.7 percent to 1178 pence on the London Stock Exchange and was the top gainer on the index on Tuesday morning.

"We view the results as overall better than expected; the buyback, although relatively small, should be incrementally accretive (about 1 percent) and the slight increase in guidance, despite the macro headwinds in some regions, should be also taken well by the market in our view," Goldman Sachs analysts wrote in a note.

Experian reported a fall in first-half pretax profit to $458 million from $534 million a year earlier. Revenue fell to $2.24 billion from $2.39 billion.

The company said foreign exchange would continue to be a headwind and it expected organic revenue growth of mid-single-digit for the year on constant currency.

Experian said the breach at a North American server was an isolated incident, which affected a single client and did not involve its U.S. consumer credit division or include payment information or bank details. (http://bit.ly/1kItIbh)

It was currently not possible to predict the scope and effect on Experian of these regulatory and government investigations and legal actions, including their timing and scale, the company said.

In the event of unfavourable outcomes, however, Experian may benefit from applicable insurance recoveries, it said.

Experian said one-off costs of directly responding to the incident were reflected in a charge of $20 million in the six months ended Sept. 30.

Attorneys general in Connecticut and Massachusetts were preparing for investigations into the breach.

The data breach had exposed sensitive personal data of some 15 million people who applied for service with T-Mobile US Inc in September.

(Reporting by Noor Zainab Hussain in Bengaluru; Editing by Gopakumar Warrier)

Stocks treated in this article : Experian plc, T-Mobile Us Inc