A&Es miss four-hour wait standard
Accident and emergency departments in England saw 92.9% of patients within four hours last week - the lowest percentage since April 2013, NHS data shows.
The government sets a quarterly target for hospitals to see 95% of emergency cases within four hours.
A&E waits have been below that level since the end of September.
The Department of Health says it recently announced extra support for A&E teams.
And officials say there is rising demand for emergency services, with more than a million extra visits to A&E last year when compared to 2010.
A Department of Health spokesman said: "The NHS is performing well despite unprecedented demand and hospitals continue to treat the vast majority of people quickly, with around 2,000 more people every day seen within the four-hour target in A&E last year compared to 2010.
"Last week we announced extra support to keep services sustainable year-round and in the long-term, we want to reduce demand by looking after people in the community."
Andy Burnham MP, Labour's shadow health secretary, said: "After a week of worrying reports about full A&E departments, it is clear hospitals in all parts of England are struggling to cope.
"Labour has repeatedly warned David Cameron and Jeremy Hunt about the danger of ignoring the warning signs.
"They have ignored the problem for far too long and now it is threatening to drag down the NHS this winter."
The standard recommends patients should be seen and then admitted to hospital or discharged within four hours of arrival in A&E.