A self-declared leader of the hacking collective Anonymous UK twice raped a woman at the Occupy London camp outside St Paul's cathedral in central in London, a court has heard.

Malcolm Blackman, 45, allegedly raped the woman once when she was asleep in a tent at the camp, and again a week later. On a separate occasion he forcibly put cable ties round her wrists to restrain her, the Old Bailey was told.

Giving evidence behind a screen, the woman said she lived in south London but spent weekends at the Occupy camp, which was set up in mid-October 2011 and then removed by police and bailiffs the following February.

She described being befriended by Blackman at Occupy: "He was part of a group calling themselves Anonymous UK. He was a welcoming sort of character, people turned to him and said, 'What do we do about this?' He seemed to be a leader sort of person."

The pair began a relationship, kept secret from others, in the run-up to the New Year. The woman said she was kissing Blackman in her tent on 14 January when he put cable ties over her hands and forced her onto the floor. Breaking down in tears she said: "He pulled my hands behind me, grabbed hold of my arms and put something around my wrists and tied them very tightly."

The woman said she was crying at the time but felt too shocked and afraid to protest too vigorously: "I told him he's hurt me, but he didn't seem bothered, he just said next time we'll have to use a code word. I just got dressed and lay there crying."

The following week, the woman said, she fell asleep talking to Blackman in the tent and woke up to find him raping her. She said: "I was scared of how he would react if I told anyone. I had seen him get angry with other people in the camp, and I thought if I started talking about it he wouldn't agree."

She said she was raped again by him a week later. Her testimony was to continue on Friday.

Blackman, from Weston-super-Mare, denies two counts of rape. The trial continues.

• This article was amended on 26 April 2013. The original placed Weston-super-Mare in Avon, a county that was abolished in 1996.