The US State Department said in a letter made public Tuesday it would weigh the results of a probe into Bahrain's protest crackdown before pursuing a planned arms sale to the kingdom.

Assistant Secretary of State David Adams assured Democratic Senator Ron Wyden, a leading critic of the $53 million deal, that Washington would look closely at a special commission's findings into alleged human rights abuses.

"The department will review the commission's findings carefully and assess the government of Bahrain's efforts to implement the recommendations and make needed reforms," Adams said in the letter.

"We will weigh these factors and confer with Congress before proceeding with additional steps related to the recently notified arms sale," Adams said in the message, which Wyden's office made public.

The commission was due to report back by October 30 on the mid-March crackdown by Bahraini security forces that authorities say left 24 people dead, including four police officers. The opposition puts the toll at 31.

Wyden, who earlier this month introduced legislation to bar arms sales to Bahrain until it addresses "alleged human rights violations" since protests flared in February, vowed to keep fighting.

"We're not going to back off in the least," Wyden told AFP, saying that opponents of the transaction would soon get together to plan their next move.

At the State Department, spokesman Mark Toner acknowledged congressional unease with the planned sale but vowed to consult lawmakers going forward and said it could be "months" before the kingdom sees a first shipment.

"There are several procedural steps that remain before this equipment, which, I would add, is for Bahrain's external defense purposes, can take delivery of any equipment listed," he told reporters.

Bahrain, where a Sunni monarchy has ruled over a majority Shiite population for decades, is located strategically in the Gulf opposite Iran, and houses the headquarters of the US Fifth Fleet.