The Centre for Covid-19 Situation Administration (CCSA) is calling on restaurants to follow restrictions on dining-in, as it admitted that a fourth wave of infections will soon sweep through the country.

Gen Natthapol Nakpanich of the CCSA said on Wednesday a fourth wave is imminent because the Delta variant which was first detected in India is rapidly spreading domestically -- a fact worrying experts at Siriraj Hospital.

Health authorities has found the Delta variant is quickly making inroads against the Alpha strain, which was once the most commonly detected Covid-19 variant in Thailand.

Experts recommended new measures which the government quickly put in place last weekend with little notice to affected businesses -- a move which drew heavy criticism from business owners.

Restaurant owners and operators, for example, protested against the sudden announcement, which left them little time to prepare.

Many had stocked up on fresh ingredients the night before the ban, only to wake up and be told that no dine-in would be allowed for a month.

The dine-in ban began on Monday.

On Wednesday, Gen Natthapol urged restaurant owners and operators not to join a campaign on social media which asks restaurants and eateries to defy the dine-in ban.

Organisers said on Facebook the campaign will be launched in three stages. Stage 1 will see the opening of 10-15 participating restaurants and eateries in each Bangkok district where live music will be played, but patrons would be limited to no more than 20.

In Stage 2, alcohol will be served with businesses opened to close friends and regular customers only.

In Stage 3, restaurants and beer gardens will be set up on roads, where protest speeches will be made.

The organisers said they have hired lawyers to help participating restaurants and eateries in court for breaking the rules.