British intelligence and law enforcement officials have passed on a grim assessment to their U.S. counterparts, "It will be a miracle if there isn't a terror attack over the holidays in London," a senior American law enforcement official tells ABCNews.com.

British police have been quietly carrying out a series of key arrests as they continue to track at least six active "plots" tied to what they call "al Qaeda of England."

Officials said they could not cite any specific date or target but said al Qaeda had planned previous operations during the Christmas holidays that had been disrupted.

"It is not a matter of if there will be an attack, but how bad the attack will be," an intelligence official told ABCNews.com.

Authorities say they are seeking at least 18 suspected suicide bombers.

“They hope they are one step ahead, but they seriously fear they may be one step behind," the senior American official said.

British law enforcement and intelligence officials say the ongoing plots have been in the planning stages for at least three years.  The officials say the plots are all connected and track back to al Qaeda commanders in Pakistan who have been recruiting and training British citizens of Pakistan descent.

A report by "Newsweek" says that American al Qaeda figure Adam Gadahn has served as a translator of a 12-member team of Western recruits, the "English brothers," said to be preparing an attack that would be much bigger than last year's attack on the London subway system.

U.S. officials say the "Newsweek" report is, in many respects, parallel to intelligence reports they have been receiving.

British Home Minister John Reid recently told reporters that it was "highly likely" that terrorists would attempt an attack before the first of the year.   

Mainland Europe is also on high alert with one French intelligence officer stating that “all the emergency lights are blinking red” – “I have not seen this before, but reminds me of the pre 911 period”.

European authorities have disrupted dozens of terrorist attempts since the July 2005 London bombings and have far more suspected radicals under surveillance than at any point since 9/11, The Washington Post reports.

Also last week, Spanish authorities broke up a cell of Islamic militants who were said to be plotting attacks on an arms depot and a supermarket.

In France, authorities are increasingly wary of an Algerian-based network, the Salafist Group for Preaching and Combat, which recently declared an alliance with al-Qaida, according to the Post.

Officials said this week that they have arrested 76 suspected members of the group in connection with three plots, including one to bomb the Paris subway.

Also to reiterate the intelligence communities fears, a new videotape has surfaced of al-Qaida’s second-ranking leader Ayman al-Zawahiri vowing  that the Algerians would soon defeat the "secularist sons of France.”

Zawahiri singles out Britain and the UN along with the West in general for all that is wrong with the Palestinian question stating it is “89 years since the Balfour Declaration, in which someone who didn’t own the Holy Land of Palestine gave it to someone who didn’t deserve it”.  He continues, “That historical event which we must not allow to pass from memory, and which we must transmit from generation to generation, in order that we be aware of the extent of the animosity of Britain and the Crusader West in general to the Muslim Ummah…”

This is probably the most urgent of all Al Qaeda potential plots that has come about since the bombings in Madrid and London.  Britain seems to be the main target and with streets packed to the rafters with Christmas shoppers and the sales after Christmas Day.  Also the fact Tony Blair, a hated infidel to Zawahiri and his gang, will be leaving office in the coming months - Al Qaeda will want to punish him before he goes.  Police and intelligence agencies will be holding their breath.  

To view the full transcript of the Zawahiri Tape please go to:

http://www.lauramansfield.com/j/zawahiri_122006.asp