Kouvelis did not specify what particular demands he objected to. A government official said on condition of anonymity that the troika is pressing for further reductions in compensations paid to laid-off workers, and a freeze in automatic salary increases due to tenure. The official was not authorized to discuss the issue on the record.Kouvelis argued that further dilution of labor rights was more than austerity-fatigued Greeks can take, and will worsen a five-year recession and record-high unemployment. "I cannot accept such demands," he said. Greece is heading for a sixth year of recession. Unemployment is around 25 percent, the highest in decades. A finance ministry official said senior troika negotiators would leave Athens on Wednesday to attend this week's EU summit in Brussels, but talks would continue with lower-level troika representatives. A different ministry official said the senior negotiators were not expected back in Athens. "We hope to reach an agreement through e-mail exchanges over the next few days," he said. Labor unions have reacted to nearly three years of bitter austerity measures with a string of general strikes and protests, often violent. A new general strike on Thursday will halt or disrupt most public services and transport schedules. Journalists will be on strike Wednesday, halting news broadcasts and preventing the publication of the next day's newspapers. Earlier Tuesday, Greece raised â¿¬1.625 billion ($2.11 billion) in an auction of 13-week treasury bills at a slightly lower rate of 4.24 percent. ___ Derek Gatopoulos contributed to this report.