Mumbai, In a huge shocker, Maharashtra registered 12 deaths and a staggering 552 new Covid-19 cases, officials said here on Sunday.

This has taken the state's death tally to 223 and the number of positive cases surpassed the 4,000 figure to touch 4,200 - the highest single day spurt till date.

Among the deaths, six were recorded in Mumbai, four in Nashik, and one each in Solapur and Ahmednagar districts.

The over 550 jump in new positive cases is the highest after the previous high of 352 notched on April 13, creating concerns in different quarters.

As per the Health Department bulletin, Mumbai alone accounted for 456 new cases over Saturday's figures, though the BMC has stated 135 new cases.

The fatalities included 8 women and 4 men, and a majority had other serious ailments like diabetes, hypertension, heart problems, asthma, etc.

The Mumbai Metropolitan Region continued to cause worries with 148 Covid-19 deaths and 3,214 positive cases till date.

Pune Division follows at a distant second slot with 55 dead and 637 patients.

The next is Nashik Division with 10 deaths and 121 positive cases, followed by Nagpur Division with one fatality and 72 patients.

On the positive side, 142 fully cured patients - again a record - returned home on Sunday, taking the number of those discharged to 507 till date.

The number of people in home quarantine shot up from 82,299 on Saturday to touch 87,254, but those in institutional quarantine decreased from 6,999 to 6,743.

The government added 24 new containment zones to take the state's total to 368, while 6,359 teams have surveyed a population of nearly 2.40 million so far.

As the Mumbai figures mounted sharply again, Leader of Opposition Devendra Fadnavis reiterated that Chief Minister Uddhav Thackeray should direct the BMC to strictly adhere to ICMR guidelines for Covid-19 testing, failing which the city could face a huge risk of spread.