An alleged Russian 'agent' has been held without bail after appearing in a court in the US.

29-year-old Russian citizen Maria Butina was arrested in Washington DC on Sunday, and appeared in court again this afternoon.

She is accused of conspiring to act as an unregistered Russian agent "by developing relationships with US persons and infiltrating organisations having influence in American politics".

Ms Butina is alleged to have been in contact with suspected Russian intelligence officials.

In court documents, Ms Butina is accused of offering an unnamed individual "sex in exchange for a position within a special interest organisation".

It's also alleged there is evidence that she is "well-connected to wealthy businessmen in the Russian oligarchy".

The US government claims Ms Butina is a flight risk who could flee if granted bail.

Prosecutors allege that the risk is "heightened due to her connection to suspected Russian intelligence operatives".

Her lawyer Robert Driscoll said: "While we respect the court, we strongly disagree that there were no conditions of release short of incarceration to detain an innocent student before trial."

The FBI has claimed Ms Butina and a Russian official "took steps to develop relationships with American politicians" to establish back channel lines of communications, in order for Russia to "penetrate the US national decision-making apparatus".

If found guilty of conspiracy, Ms Butina faces a maximum of five years in prison.

The case is not connected to the ongoing special counsel probe into alleged Russian interference in the US election.

Commenting on the case, the Russian ministry of foreign affairs accused the FBI of "whipping up anti-Russia hysteria".

#Zakharova: It looks as if the FBI, instead of carrying out their responsibility of fighting crime, is implementing a political put-up job set to it by forces that are whipping up anti-Russia hysteria in the US

— MFA Russia ???? (@mfa_russia) July 18, 2018