India's capital New Delhi on Sunday extended its lockdown as the country's COVID-19 crisis grew with infections and deaths hitting record highs.

The vast nation of 1.3 billion people recorded 349,691 fresh cases and 2,767 deaths -- the highest since the start of the pandemic.

The northern megacity -- home to 20 million people and the worst-hit in India -- had imposed a weeklong lockdown on Monday as hospitals beds and oxygen supplies ran out.

"We have decided to extend the lockdown by one week," Delhi Chief Minister Arvind Kejriwal said in a video statement.

"The havoc of corona(virus) continues and there is no respite. Everyone is in favour of extending the lockdown."

The announcement came as the healthcare system struggled to cope with the huge spike in cases, with reports of overwhelmed hospitals, severe oxygen and medicine shortages, and patients' families pleading for help on social media.

There has been growing criticism of the government over allegations that it was caught underprepared ahead of the surge.

On Sunday, Twitter confirmed it had withheld dozens of tweets critical of the unfolding crisis at the request of the Indian government.

The social media giant said the tweets were blocked in India after a legal demand from New Delhi, months after similar action was taken against comments critical of the government's new agriculture laws that had sparked violent protests.

Some tweets involve remarks, including from regional opposition lawmakers, about the overwhelmed healthcare system, which has seen patients die from oxygen shortages.

"When we receive a valid legal request, we review it under both the Twitter Rules and local law," Twitter said in a statement.

"If the content violates Twitter's rules, the content will be removed from the service. If it is determined to be illegal in a particular jurisdiction, but not in violation of the Twitter rules, we may withhold access to the content in India only."

In the last seven days, India has recorded more than two million cases -- an increase of 58 percent on the previous week, according to data compiled by AFP.

Other Indian cities under lockdowns, night curfews, or other restrictions to try and contain the spread of the virus include the financial hub Mumbai.

The government has stepped up its efforts to provide oxygen supplies through special trains and airlifts of containers from other countries.