FTP Over TLS – How to Connect Using SFTP

I have been wasting more then an hour on this now and I think this should be really simple…

I have an azure website that allows me to connect and deploy to it using sftp. I can connect to it fine using FileZilla with the following settings:

• Host: The host given by azure portal
• Port: Empty
• Protocol: FTP – File Transfer Protocol
• Encryption: Require implicit FTP over TLS
• Logon Type: Normal
• User: The username given by Azure portal
• Password: The password given by Azure portal.

I don't want to connect to it using FileZilla though. I want to move files over using the command line. I have been trying to use sftp, ftp and scp all without success. In the end they all fail with the following:

$ sftp -v -oPort=990 user@xxxxx.ftp.azurewebsites.windows.net
OpenSSH_7.9p1, OpenSSL 1.0.2r  26 Feb 2019
debug1: Reading configuration data /home/rg/.ssh/config
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 17: Applying options for *
debug1: Connecting to xxxxxxx.azurewebsites.windows.net [xxx.xxx.xxx.xxx] port 990.
debug1: Connection established.
debug1: identity file /home/rg/.ssh/id_rsa type 0
debug1: identity file /home/rg/.ssh/id_rsa-cert type -1
debug1: identity file /home/rg/.ssh/id_dsa type -1
debug1: identity file /home/rg/.ssh/id_dsa-cert type -1
debug1: identity file /home/rg/.ssh/id_ecdsa type -1
debug1: identity file /home/rg/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/rg/.ssh/id_ed25519 type -1
debug1: identity file /home/rg/.ssh/id_ed25519-cert type -1
debug1: identity file /home/rg/.ssh/id_xmss type -1
debug1: identity file /home/rg/.ssh/id_xmss-cert type -1
debug1: Local version string SSH-2.0-OpenSSH_7.9
ssh_exchange_identification: Connection closed by remote host
Connection closed.
Connection closed

I have tested that the OpenSSL version in use supports TLS 1.2. Neither is the host in the known hosts with another fingerprint.

I hope somebody can help me here.