Four men have appeared in court charged with an alleged terror plot to shoot to kill police officers or soldiers on the streets of London, and with pledging allegiance to Islamic State.

The men, all from London and arrested earlier this month, are accused of scoping out a police station and army barracks, and obtaining a handgun and ammunition.

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A fifth man appeared at Westminster Magistrates Court on Friday at the same time, charged with firearms offences.

Prosecuting lawyer Mark Dawson told the court the case revolved around an alleged plot “to shoot, to kill, police officers or soldiers on the streets of London,” according to the BBC.

The men were brought to court under heavy security as a helicopter flew overhead, and appeared in the dock flanked by 10 police officers.

Their lawyers did not apply for bail and all were remanded in custody to appear at the Old Bailey central criminal court on October 27.

The four main suspects are Nyall Hamlett, 24, Tarik Hassane, 21, Suhaib Majeed, 20, and Momen Motasim, 21.

They are accused of carrying out activities between July 8 and October 7 with the intent of committing acts of terrorism or assisting others to commit such acts, police said.

In a list of charges, Scotland Yard said the four had conducted “hostile reconnaissance” of a police station and an army reservist barracks in west London.

They allegedly took “an oath of allegiance to the group IS”, listed in the UK as a banned organisation.

They are also accused of deciding to act on a fatwa by IS spokesman Abu Mohamed al-Adnani and having “extremist jihadi material” in their possession.

The fifth man, Nathan Cuffy, 25, is charged with transferring a weapon fitted with a silencer and ammunition to Hamlett on September 23.

Two men aged 21 and 20 arrested on October 7 as part of the investigation were released from custody on Monday, and another man was released on Friday after prosecutors advised there was insufficient evidence to charge him.

Meanwhile, a 19-year-old woman has been released on bail pending further inquiries.

Britain estimates around 500 Britons are fighting with IS jihadists in Iraq and Syria, and has warned of potential attacks by radicalised fighters when they return home.