A second school has received "malicious communication" after a string of bomb threats put another school on high alert this morning.

Officers were at the front gate of Brighton's Cardinal Newman Catholic School this morning after a "bomb threat" said to be from a terrorist group was sent to students ahead of their lessons.

But students at another secondary school in the city were also targeted by similar messages, according to a senior city councillor - who said she is taking these threats "extremely seriously."

The Argus: Cardinal Newman believes the messages were the work of a student at the schoolCardinal Newman believes the messages were the work of a student at the school (Image: Andrew Gardner / The Argus)

The second bomb threat was sent to Blatchington Mill School shortly after 9.30am today and was said to be similar to the ones received by Cardinal Newman students - some of which are as young as 11 years old.

Emails were sent to pupils and staff at Cardinal Newman suggesting the presence of "two highly explosive devices" in the school, with the anonymous sender - purporting to be from terrorist group the Islamic State - demanding a ransom of £30,000.

The Argus: The first email sent to students and staff at the secondary schoolThe first email sent to students and staff at the secondary school (Image: Supplied)

Sussex Police were contacted and investigated the legitimacy of the threats, but determined that they lacked "credibility" according to principal Claire Jarman.

She said: "Our technical support and senior leadership teams worked on this issue through the night, it became apparent that the emails were being sent by someone with knowledge that only a student could have, so please trust us when we say we know the threat is both a malicious communication and not a credible one. 

"None of this is to mitigate or diminish how distressing it would be to receive those emails and we are particularly mindful of Newman families who have come here having suffered the most awful threat levels in other parts of the world and came to Brighton as a safe place."

The Argus: Officers outside Cardinal Newman in HoveOfficers outside Cardinal Newman in Hove (Image: Andrew Gardner / The Argus)

Councillor Lucy Helliwell, co-chair of the children, families and schools committee at Brighton and Hove City Council, said: “We are aware of malicious communications sent to Cardinal Newman school and are working with them to offer any support they may need.

"We take the safety of our children and staff extremely seriously.

“We’re in contact with Sussex Police as the lead agency whose officers established that this was a hoax threat. "

The Argus: A police car outside Cardinal Newman's front gateA police car outside Cardinal Newman's front gate (Image: Andrew Gardner / The Argus)

Students at Cardinal Newman were given the choice to take the day off as the principal said "some families would have felt fearful of sending their child in."

Cllr Helliwell added: “We’re also aware of similar malicious communications sent to Blatchington Mill School and are offering the same support."

A spokeswoman for Sussex Police said: "Police received reports of a bomb threat at Cardinal Newman School, Hove at about 5.40pm on Monday 9 October.

"At around 9.35am on Tuesday, 10 October, police responded to a report of a bomb threat at Blatchington Mill School, Hove.

"Both threats are believed to be hoax and from separate sources.

"The public can expect to see a heightened police presence around both schools today, whilst neighbourhood officers offer support and reassurance to students, staff and parents/guardians."