Waitakere Hospital's emergency department was forced into partial closures during its normal opening hours 52 times in the first five months of this year.
Short-staffing and financial constraints are blamed for the restrictions on the department's services and its failure so far to become an around-the-clock operation.
Waitakere-based National list MP Paula Bennett told Parliament yesterday it was a "crisis", to which Associate Health Minister Steve Chadwick replied that she was being "alarmist".
Ms Bennett: "How does the minister respond to the mother who turned up to the emergency department with her son having an asthma attack in her arms and who was turned away to White Cross."
She had no transport and had to carry her child down the road to the after-hours clinic.
Mrs Chadwick was unaware of the case and said the Government would look into it urgently.
The emergency department was intended to open around the clock when it was commissioned in 2005 as part of the hospital's $60 million upgrade, but the Waitemata District Health Board has not considered it has enough money to provide this service, which would also require extending theatre and laboratory services.
The latest plan is for the department to become 24-hour by 2010. It now closes between 10pm and 8am.
But, if it has too few doctors during opening hours because of vacancies, sick leave or having to top up staffing at North Shore Hospital, it sometimes "diverts" patients after assessment to other hospitals or, with a voucher for free care, to the nearby White Cross primary care clinic.
Diversion, effectively a partial closure, happened 15 times in March - the highest monthly tally from January to May - for a total of 55 hours. In this period 254 White Cross vouchers were handed out.
The department has positions for 12 full-time-equivalent doctors. Four of those are now vacant.
Board chairwoman Kay McKelvie said: "We're committed to opening it 24 hours and we are working along that, hopefully starting recruitment by the end of this year."
* $60 million was spent on upgrading Waitakere Hospital.
* In 2005, this brought it to "district" hospital status, fulfilling a 40-year-old promise - almost.
* The emergency department, a scaled-back version, was intended to become a 24-hour service within months.
* The latest target for this is 2010.