Prosecutor David Kris said the new charges "underscore the global nature of the terrorist threat we face", underlining the US view that foreign-based al-Qaeda groups, rather than a rag-tag and amateurish collection of US residents, are the main threat.
Zazi, originally from Afghanistan, had admitted receiving bomb-making and weapons training from al-Qaeda in Pakistan's Waziristan region bordering Afghanistan, but no explosives were found in the New York case.
The former Denver Airport shuttle bus driver had said he would "sacrifice" himself "to draw the attention to what he said were US crimes in Afghanistan".
He pleaded guilty in February to the three charges of conspiracy to use weapons of mass destruction, conspiracy to commit murder in a foreign country and providing material support to al-Qaeda.
Court papers made clear that Zazi was not only inspired, but also directed by Pakistani-based al-Qaeda groups.
Most prominent among the accused on Wednesday was Saudi-born El Shukrijumah, charged with being one of three "leaders of al-Qaeda's 'external operations' programme dedicated to terrorist attacks in the United States and other Western countries".
The justice department claims that all three of those leaders "organised" the Zazi plot, even if only El Shukrijumah is charged.
El Shukrijumah is accused of recruiting Zazi and two other men - one who has pleaded guilty and one who is in US custody but has not yet been tried - between September and December 2008.
|Prosecutors say the men were to 'conduct suicide bombings in New York City' [EPA]
They were to "conduct suicide bombings in New York City using improvised explosive devices made from supplies such as hydrogen peroxide, acetone, flour and oil".
Ahmad, who allegedly was the "facilitator" keeping in touch with Zazi by email, oversaw the preparations, the indictment alleges.
In a final email just before leaving on his failed mission to New York from Colorado, Zazi allegedly wrote to Ahmad saying "the marriage is ready", alleged code that the plot was primed.
The New York plot was linked to the British plot by Ahmad, prosecutors said. Ahmad, an accused al-Qaeda facilitator in Peshawar, Pakistan, communicated with Zazi about the New York plot and with Naseer about a British plot.
Naseer and Rehman were among 12 men detained on terrorism charges after a raid in northwest England in April 2009.
Officials said they found surveillance photos of public areas in Manchester, but the authorities did not have enough evidence to charge the men and they were released.
Naseer was arrested again in Britain on Wednesday and is awaiting extradition to the US.
Rehman, El Shukrijumah and Ahmad are still at large. All the men charged in the indictment face life in prison if found guilty.