A commentator says the international community takes Saudi claims that it seeks to transform its economy in a structural way with a grain of salt.

Moody's has downgraded the credit ratings for two Persian Gulf states, saying the plunging crude prices have taken their toll on the oil-dependent economies.

US crude oil has slipped toward US$30 per barrel to a 12-year low as heavy oversupply showed no sign of easing.

Speculations are emerging in Iran's media that plunging oil prices have already cost the country at least $23.6 billion in terms of lost petrodollars.

Crude oil futures have plunged to their lowest level in nearly seven years amid rising concerns over a growing supply glut.

Oil prices have surged more than three percent after figures revealed that US drilling slowed, with analysts estimating that some $1.5 trillion worth of planned US production investment was uneconomical.