MPs and peers have voiced concerns about the police tactic of "kettling" protesters, ahead of what is expected to be the largest demonstration for several years on the streets of London on Saturday.
There is "considerable room for improving" frontline officers' understanding of guidelines on the use of kettling, which sparked controversy when large numbers of protesters were trapped behind police lines during recent student demos, said the parliamentary Joint Committee on Human Rights (JCHR).
In a report released on the eve of Saturday's TUC March for the Alternative, the cross-party committee also said they were "surprised" that there was no specific guidance on the circumstances in which police may be justified in using batons against the heads of protesters. They recommended drawing up guidelines and amending training to reflect this concern.
The Metropolitan Police told the committee that they were "not in a position" to reveal whether undercover officers will be deployed to mingle with protesters on Saturday.
Friday's report praised the close co-operation between the Met Police and organisers ahead of the demonstration, which is expected to attract hundreds of thousands of marchers to protest against cuts.
The Met will keep in touch with protesters via Twitter and maintain radio contact with TUC stewards during the march in the hope of ensuring a trouble-free demonstration, it said. And independent human rights advisers from the organisation Liberty will be present alongside TUC representatives in the police control room during the demonstration.
Hailing the preparations as "a model of good practice", the JCHR said: "We hope that this will be reflected in a successful and peaceful demonstration in which all participants feel that they have exercised their democratic right to protest."
But the report added: "We do however note that, when we took evidence, neither side had raised with the other the possibility of the need to use containment or 'kettling'. This was an oversight that ought not be repeated with regard to the planning of future demonstrations."
During its inquiry, the committee was told by the Met that kettling - which involves police surrounding groups of protesters and holding them for lengthy periods in a confined area - was used in recent student demonstrations because of concerns that to allow a march to move on could lead to "widespread damage and disorder".
But the inquiry also heard evidence from student leaders that kettling "terrified" protesters and caused "significant anxiety".