Four men pleaded guilty Wednesday to conspiring with an Al Qaeda-linked operative convicted of plotting to bomb the New York Stock Exchange and other targets in the United States and Britain.

The men pleaded guilty in a London court to plotting to cause explosions with Dhiren Barot, who was sentenced to life in prison in November for planning attacks on several U.S. financial targets, London hotels and train stations.

Authorities did not specify which targets the four men -- Junade Feroze, 31; Mohammed Zia Ul Haq, 28; Abdul Aziz Jalil, 34; and Omar Abdul Rehman, 23 -- were accused of plotting to blow up.

A fifth man, Qaisar Shaffi, 28, denied the charge and will stand trial next week.

The sentence against Barot, a 34-year-old Muslim convert, was one of the toughest punishments ever handed down in a British court. He was convicted of planning to use limousines packed with gas tanks, napalm and nails in the attacks. Prosecutors said the targets included the International Monetary Fund in Washington, the Citigroup headquarters in New York and London railway stations such as Waterloo, Paddington and King's Cross.

Attorneys have appealed Barot's punishment -- life in prison without the possibility of parole for 40 years -- arguing that he deserved a shorter sentence after pleading guilty.

A sixth defendant in the case, Mohammed Naveed Bhatti, 27, pleaded guilty last week, and another, Nadeem Tarmohammed, 28, has yet to be arraigned.