Nginx how to rate limit specific http method of a resource?

I have a backend service running on port 8080. There are two endpoints:

• GET /item
• POST /item

I configured Nginx in the following way:

limit_req_zone $binary_remote_addr zone=mylimit:10m rate=20r/m;

server{

    listen 81;
    root /var/www;
    
    location /api {
        location /api/item {
            limit_req zone=mylimit;
            proxy_pass http://127.0.0.1:8080/item; 
        }
    }
}

This configuration rate limits requests for both the GET and POST method.

How to rate limit only the POST method?