The troops died in three separate incidents in Helmand province.
The troops died in three separate incidents in Helmand province yesterday, taking the number of UK service personnel killed in the country since 2001 to 157.
It was the bloodiest day for British forces in Afghanistan since February 25, when three soldiers and one Royal Marine died.
The soldiers' families have been informed.
Two of the soldiers, one from 1st Battalion the Royal Gurkha Rifles and the other from 173 Provost Company, 3rd Regiment, Royal Military Police, were killed by a suicide bomber during a patrol in Gereshk yesterday afternoon.
The attack also left at least 16 Afghan civilians dead and more than 30 wounded, according to the Nato-led International Security Assistance Force (Isaf).
British military spokesman Lieutenant Colonel Nick Richardson said: "With heavy heart we report another extremely sad situation, where lives of our courageous soldiers have been sacrificed for the greater good of the Afghan people.
"Our deepest and heartfelt sympathies go to their families and loved ones and we offer our thoughts and prayers to them all at this most painful and distressing time."
Isaf spokesman Brigadier-General Richard Blanchette added: "The insurgents repeatedly and intentionally harm the innocent Afghans we are committed to protecting, in support of the Government of the Islamic Republic of Afghanistan.
"This senseless act of violence was committed with the full knowledge that a large number of Afghan lives would be lost.
"Afghan and international forces will not be deterred by these irrational insurgent tactics."
Another British soldier, from 2nd Battalion the Rifles, was killed when his Jackal patrol vehicle was hit by an improvised explosive device near Sangin last night.
The fourth soldier, from the Black Watch, 3rd Battalion the Royal Regiment of Scotland, died from a gunshot wound sustained during a patrol with the Afghan National Army near Musa Qala.