UPDATE 1-L'Espresso calls in lawyers on Berlusconi remarks

(Recasts with Berlusconi comments)

MILAN, June 24 (Reuters) - Italy's Editoriale L'Espresso said it is considering suing Prime Minister Silvio Berlusconi for urging an advertising boycott of its La Repubblica daily, prompting the premier to call the publishing group "shameless".

L'Espresso (ESPI.MI: Quote, Profile, Research) said in a statement Berlusconi had accused Italy's No. 2 selling daily, La Repubblica, of a "subversive attack against him" and called on business leaders to "boycott and stop advertising investments" at the paper.

L'Espresso said it had instructed lawyers to consider civil and criminal actions over the remarks.

The left-leaning La Repubblica has led the attack against Berlusconi in recent weeks over his private life.

This began over his friendship with an 18-year old aspiring model and intensified after an escort said she had been paid to attend his parties. She also said she had slept with the prime minister [nLN461096].

Berlusconi has denied ever paying for sex and calls the accusations against him "garbage".

The 72-year-old prime minister, who owns a publishing and broadcast empire that includes advertising arm Publitalia, responded by saying that businesses that place advertisements in such media are "masochistic".