Rating agency Standard & Poor's downgraded Saudi Arabia, Brazil Kazakhstan, Bahrain and Oman's credit ratings on Wednesday, in its second mass cut of large oil producers in almost exactly a year.

S&P cited the pressures being created by the drop in oil prices for the moves which included double-notch downgrades of Saudi Arabia to A- negative from A+ stable and stripping Bahrain of its investment grade status.

"The decline in oil prices will have a marked and lasting impact on Saudi Arabia's fiscal and economic indicators given its high dependence on oil," the ratings agency said in a statement.

The plunge in oil prices since mid-2014 had already brought a blizzard of downgrades for oil producers, including Saudi Arabia, Russia, Brazil and Venezuela, where the oil rout has raised fears of a sovereign default.

The moves were a near repeat of similar co-ordinated cuts made this time last year. The firm's head of sovereign ratings in EMEA, Moritz Kraemer, told Reuters last month that another such move was being considered.

One country that was spared this time was Russia. S&P said Moscow's fiscal buffers gave it more leeway, though it could still cut its BB+ rating again if those were eroded faster than expected or if international sanctions were "significantly" tightened again.

Brazil was kept on a negative outlook, meaning a roughly 1-in-3 chance of another cut as its rating dropped one notch to BB from BB+.

However, it was Brazil's political difficulties as much as the economic pressures from falling oil prices that were cited for the move.

For the Middle East there is far more intense pressure from low oil because many currencies, including the Saudi riyal, are pegged to the dollar, limiting scope for currency weakness that could stimulate the economy.

Authorities are also having to dig into reserves to keep spending at levels that support their highly dependent economies.

Like Saudi Arabia, Bahrain saw its rating cut two notches. Significantly, though, it also lost investment grade as it went to BB from BBB-.

Oman was lowered two steps as well to BBB- stable from BBB+ negative while Kazakhstan was cut one notch to BBB- from BBB but left on a negative outlook due to concerns about inflation, exchange rate pressures and banking sector stability. – Reuters