Haringey police say they are stepping up patrols at Alexandra Palace's ice rink and urging skaters to arrange lifts home in the evenings after two separate robberies on skaters in the past two weeks.

Two pairs of females have been targeted after leaving the rink on weekend nights. In the most recent case, at 11pm last Saturday, two 14-year-old girls from Enfield were approached by a group of four other teenagers.

After one of the girls refused to hand over her mobile phone, she was punched and kicked. The suspects, three girls and boy, all aged 12 to 16, made off on the W3 bus towards Wood Green. Police have made four arrests in relation to the assault and robbery.

Two other teenage girls were robbed in similar circumstances after leaving the ice rink on Saturday, February 18.

Police do not believe the robberies were carried out by the same group.

As part of their crackdown, police have increased their presence on weekend evenings to protect young skaters leaving Alexandra Palace. They have also been viewing CCTV footage from the palace and have made one arrest for possession of an offensive weapon.

A Haringey police spokesman said: "We urge skaters to be vigilant when leaving and to arrange lifts home with parents or guardians to prevent being targeted."

A spokesman for Alexandra Palace said he was surprised to hear of the police's concerns and stressed police had not informed the palace management of any particular problems.

The spokesman added the planned redevelopment of the palace would improve security.

"At the moment, 50 per cent of the palace is derelict and out of use. But with the redevelopment more of the palace will be brought into use."

If you have any information in relation to these two recent incidents, call Haringey police on 020 8345 0763.