According to her husband, Mrs Li, who suffered from epilepsy and was wheelchair-bound after suffering a stroke, had fallen into a coma in Xian on Sunday, November 4. A doctor had administered an injection to her.

Before she lapsed into unconsciousness she had expressed a wish to return to Hong Kong to see her intellectually handicapped son.

Mr Sheung said he had travelled with Mrs Li, who was unconscious in her wheelchair and wearing a surgical mask, on the train journey from Xian and had arrived in Shenzhen about 5am on Wednesday.

He said she was unconscious when he pushed her through the border checkpoint and he could not say whether she was dead at the time or not.

'As I presented our (travel) permits at the immigration counter, the immigration officer asked me to pull up her hat, then he took a look at the picture (in the permits) and let us go,' he said.

'The officer did not ask me what happened to her.'

Mr Sheung said he did not ask for assistance because 'I wanted to take her home as soon as possible. This was her wish'. He said he had planned to seek treatment for his wife in Hong Kong and did not send her to hospital on the mainland because they could not afford treatment there.

But he said: 'If it is necessary to find out who should take the responsibility, I think I should take this because I didn't explain her condition clearly to them [immigration officers].'

Mr Sheung said he did not ask for emergency services at the border because 'I did not want to trouble them'.

Immigration Services Officers Association chairman William Lee Hok-lim said he did not see any problem with officers' response to the pair at the border.

'The person who is accompanying an unconscious person knows what the best medical treatment is,' he said.

'If the accompanying person does not ask for help and our officers do not see any reasons [for concern], it may delay the treatment if we raise questions.'