ATHENS (AFP) - Greece's runaway debt is on a "knife's edge", the IMF's mission chief to Athens said in an interview on Sunday as he called for an "invigoration" of structural reforms in the vast Greek public sector. "The Greek debt is sustainable but it is, as we say, on a knife's edge," Poul Thomsen, deputy European director of the IMF, told Ethnos daily. "Policies must be applied as planned, or the sustainability of the debt will be placed in doubt," he said. "The programme will not continue to deliver the desired results without a real invigoration of structural reforms in the public sector to ensure a further deficit reduction, and without further reforms to get economic recovery going next year," Thomsen said. The EU and International Monetary Fund bailed out Athens last year with a package worth $160 billion but the country remains in serious financial difficulty, with credit rating agencies having demoted Greece's bonds to junk status.