Some of the key developments in Wednesday's action include:

• 1042 GMT: The first of eight giant US B-52 bombers fly out of RAF Fairford in Gloucestershire.

• 1110: Defence Secretary George Robertson tells the Commons defence select committee: "This is one of the gravest days that we and our Nato colleagues have faced."

• 1240: Reports of warning sirens sounding in Pristina, the capital of Kosovo.

• 1400: In a statement from the EU leaders summit in Berlin, Tony Blair, warns: "Aggression must not be rewarded. An aggressor must know that he will have to pay a high price."

• 1453: Nato air attacks against Yugoslavia begin with explosions reported from the Kosovan capital Pristina.

• 1511: A B-52 bomber arrives back at Fairford Air Force base, some eight and a half hours after eight planes took off from the base.

• 1919: Air raid sirens reported to have been sounded in both Pristina and Belgrade, with the Kosovan city plunged into darkness.

• 1926: Second B-52 bomber arrived back at RAF Fairford.

• 1928: In Berlin, Mr Blair says: "I can confirm that Nato air strikes against Serb forces have begun and that UK forces are engaged in this action."

• 2005: British sources in Berlin confirm that RAF ground attack Harrier GR7 aircraft were involved in the sorties against the Serbs and that the submarine HMS Splendid - equipped with sea-launched cruise missiles - was also involved.

• 2040: The third B-52 bomber lands at RAF Fairford. It is believed to be the first of the six giant planes which were involved in the air strikes. The fourth lands five minutes later.

• 2100: Deputy Prime Minister John Prescott makes an emergency statement in the Commons saying the British Harriers involved in the attack had returned safely to their base and, in conjunction with cruise missiles from HMS Splendid, had attacked Serbian air defence systems.

• 2110: The sixth and final B-52 lands back at RAF Fairford.

• 2215: The first B-52 air crew to arrive back say the mission was a success.