Can the employer force the employee to finish the notice period after visa expires?

Hi.

I resigned and I have 60 days notice period as per my contract. My visa will expire in 40 days.

Should I work for the remaining 20 days after my visa expires?

I got an offer from another company. But my present company asks me to work for the remaining 20 days after my visa expires (in visa buffering days).

I'm ready to pay for the remaining days. But they not accepting.

I need to leave early, What I should do in this case?