Julian Assange, the founder of WikiLeaks, must be extradited to Sweden to face accusations of rape, sexual molestation and unlawful coercion, the high court in London heard.

Clare Montgomery QC, appearing for the Swedish prosecution authority on the last day of Assange's appeal against extradition, said complaints against him showed a lack of consent during a string of sexual encounters in Stockholm last August. She said the charges set out on the European arrest warrant and supported by witness statements amount to valid allegations.

Speaking to a packed court four at the Royal Courts of Justice before Lord Justice Thomas and Mr Justice Ouseley adjourned to consider their verdict, she spelled out in graphic detail Assange's alleged behaviour and said the two female complainants known as AA and SW described "circumstances in which they did not freely consent without coercion".

"They were coerced, either by physical force or they were trapped into a situation where they had no choice," Montgomery said. "AA says in her case the prelude to the offence was Mr Assange ripping her clothes off, breaking her necklace, her trying to get dressed again and then letting him undress her." He then had sex with her after pinning her arms and trying to force her legs apart to insert his unprotected penis, which she did not want, she said.

In an increasingly hard fought legal battle, Assange's counsel, Ben Emmerson QC, hit back at what he said were attempts by Montgomery to characterise him as having "19th-century conceptions of consent". It was "crazy" of Montgomery to isolate a moment of lack of consent within sexual encounters that were otherwise consenting. He said police reports in Sweden showed SW had told a friend, Marie Thorn, that she felt police and others around her "railroaded her" into pressing charges. She had only wanted the police to force Assange to take a blood test after she became worried about HIV after unprotected sex with him, he said.

Emmerson said a friend of AA, Donald Bostrom, said "she didn't say at all she had been exposed to abuse and didn't even want to go to the police", and a charge of sexual molestation arising from Assange sharing a single bed with AA was also unfounded.

The European arrest warrant said Assange "deliberately molested the injured party on 18 August 2010 by acting in a manner designed to violate her sexual integrity".

In an interview, AA said Assange undressed below the waist and rubbed his erect penis against her. She found it "strange" and "awkward" and moved to sleep on a mattress on the floor. But Assange's erection was normal, Emmerson told the court.

"He's lying beside her in a single bed my lord," he said. "Men will get erections involuntarily and at different times during a night's sleep. If she chooses to spend a night in a single bed with a man there is a strong possibility she will come into contact with an erect penis. I don't mean that as a joke."

"I agree with you," said Thomas.

However, Montgomery told the court the definition of an extradition offence "means the conduct complained of. It has nothing to do with the evidence."

Thomas appeared to concur: "We are not concerned with whether this is a good case or a bad case but whether what is charged amounts to a crime."

In one of several criticisms of the Swedish authorities, Emmerson said: "The clearest possible facts have been concealed through the terminology of the warrant. That is wrong and it is the responsibility of this court to put it right."

Assange left court without comment and returned to Norfolk to continue his house arrest. A verdict is expected in around a month.