The chief of the EU's monitoring mission said Sudan had "not reached all [standards] but some of them".
The polls were intended to effect a democratic transformation in Africa's largest country.
The complicated ballot has already been heavily criticised by the Sudanese opposition and local observers. Final results are expected on Tuesday.
Speaking at a news conference in Khartoum, EU mission chief Veronique de Keyser said: "Turnout is very high, 60%, but with significant deficiencies.MORE HERE