AMSTERDAM Feb 13 (Reuters) - Dutch telecoms firm KPN apologised on Monday for disabling 2 million email accounts after a cyber attack and acknowledged its technology was not up to scratch.

The move was KPN's latest setback this year following a profit warning, a negative ruling on a contract and the sudden departure of its chief financial officer on Jan. 3 over a dispute about internal governance.

The largest telecommunications provider in the Netherlands was already struggling to reverse a decline in revenues, profit and market share in its fixed-line and mobile operations.

"For you and two million other KPN clients it was very difficult and unwelcome. For this we would like to apologise," KPN said in a series of advertisements in Dutch newspapers.

"We would like to apologise two million times."

KPN's Dutch head Joost Farwerck, who was appointed to the job only last week, said in a separate statement the performance of KPN's technology was unacceptable.

"We will shortly implement a number changes in the management of our IT organisation to increase quality and effectiveness," he said. "The last few weeks have unmistakably shown the necessity for this."

KPN discovered a security breach in January and said it had taken measures to secure its servers, protect data and notify authorities.

On Friday it said it disabled 2 million client email accounts as a precaution after discovering personal data of more than 500 of its customers posted online.

Three weeks ago, it cut its core profit expectations for 2012 and scrapped a 2012 share buyback programme to pour money into its struggling domestic business.

Chief Executive Eelco Blok, who took the helm in April 2011 and has faced criticism from analysts, regulators, politicians and the public, said the performance of the company had been mixed.

"After a turbulent weekend we can say that we have done things good and bad. In the area of our systems, security, as well the areas of informing and communicating with our clients." he said in a statement.

Some of KPN's email customers took their anger to local media, websites and social media networks over the weekend.

Some Dutch media reported on Saturday that the personal data found online was not from KPN but an online retailer.

KPN was not available to confirm on Monday where the data originated. (Reporting by Gilbert Kreijger and Roberta Cowan; Editing by David Cowell)

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