European Union President Herman Van Rompuy said on Wednesday that negotiations on Greece's debt are well on track, and there is no question of restructuring it.

Negotiations are going on, they are well on track, and no question about restructuring of the debt, Van Rompuy told a news conference in Tokyo, where he is on a four-day visit.

He said a meeting would be called of heads of state of the eurogroup, or euro zone, around May 10.

Sources in the Spanish-led EU presidency had said European Union leaders were discussing the possibility of holding a special summit in Brussels on May 10 to activate an aid package for Greece.

Rating agency Standard and Poor's slashed Greek debt to junk status on Tuesday and also downgraded Portugal, as investors worried political pressures could block a multi-billion euro bailout of Greece.

Markets are not convinced that governments will have the political will to reach and sustain an agreement on the aid, especially in Germany, where public opinion is strongly against helping Greece and where Chancellor Angela Merkel's party risks defeat in a regional election on May 9. (Reporting by Yoko Kubota)