Six people were arrested and released without charge following the Easter Monday commemoration at City Cemetery, which was addressed by a masked spokesman for the Real IRA.

He read out a statement pledging that the organisation would continue its campaign of violence against the police and army in Northern Ireland.

The PSNI made no attempt to make arrests during the commemoration, with no officers visible on the ground - although they did monitor events from a helicopter hovering overhead.

It was only when the event ended that police took action, arresting six people who were taken to Antrim Serious Crime Suite for questioning.

Gregory Campbell, the DUP's spokesman on security issues, told UTV the police need to adopt a more serious approach.

He said: "I think that unless we see some sort of response now in terms of further arrests, unless we see that leading to a non-repeat of this, then we have got to have a different approach."

However, police said they "took the decision to run a low-key operational response" at the 32 County Sovereignty Movement commemoration.

Local area commander Chief Inspector Gary Eaton said: "Any alleged breaches of criminal law reported to police or coming to our attention will be rigorously and thoroughly investigated.

"The PSNI work to ensure that all their actions are appropriate, proportionate and lawful. Our priorities are to protect the public, preserve public order, uphold the human rights of all and gather evidence of any wrong-doing."

Several hundred dissident republican supporters watched as the colour party marched to the cemetery on Monday, where wreaths were laid.

The spokesman, dressed in a balaclava and black combat gear, said Óglaigh na hÉireann would continue to attack "Crown forces" and "British interests and infrastructure".

His words were met with applause by the crowd.

Police have appealed for anyone with information to come forward.