Activist investor Guy Wyser-Pratte said he is seeking board seats at French phone directories company PagesJaunes ( id="symbol_PAJ.PA_0"> PAJ.PA ) to force its biggest shareholder - U.S. private equity firm Cerberus - to cut the group's debt. PagesJaunes has been struggling with big debts since a private equity buyout of the company in 2006. The firm has also had to cope with the impact of the Internet on its printed directories businesses. Wyser-Pratte, a U.S. investor who focuses on European companies, has built up a 0.85 percent stake in PagesJaunes, which he said was enough to mount a challenge to Cerberus CBS.UL. Cerberus became PagesJaunes' biggest shareholder, with 28 percent of voting rights, via the purchase of debt from Mediannuaire, a holding company controlled by Goldman Sachs Group ( id="symbol_GS.N_2"> GS.N ) and private equity firm KKR & Co ( id="symbol_KKR.N_3"> KKR.N ). A restructuring earlier this year has cu