The US Senate on Thursday blocked a resolution introduced by Democrats aimed at stopping the war on Iran unless Congress authorizes combat operations.

The vote reflects growing concern in Congress, even among Republican lawmakers loyal to President Donald Trump, over the conflict.

Follow the story: Heated session in the Senate.. sharp disagreements over funding the war with Iran

The Senate voted 49 to 47 against moving forward with the war powers resolution.

The Republican-controlled House of Representatives on Thursday backed legislation directing President Donald Trump to halt any US military action against Iran.

The vote was 214 to 208 in favor of the war powers resolution after four Republicans joined Democrats in supporting it.

The resolution, introduced by Democratic Representative Pramila Jayapal, directs Trump to 'cease the use of the United States Armed Forces in hostilities' against Iran unless Congress authorizes such action.