MEXICO CITY, Oct 18 (Reuters) - Mexican Energy Minister Rocio Nahle said on Sunday that construction of the country's new refinery at the southern Gulf coast port in Dos Bocas was almost a quarter completed.

A confidante of Mexican President Andres Manuel Lopez Obrador, an energy nationalist who favors a stronger state role in the sector, Nahle said construction was 24% completed and had entered the next phase. The government has said it aims to finish the refinery by 2022.

The government has put an $8 billion price tag on the refinery, but independent analysts have said that figure is low.

Investors and ratings agencies have criticized the project, arguing that resources should go instead to more profitable parts of state oil company Petroleos Mexicanos, or Pemex .

"We want to be self-sufficient," Lopez Obrador reiterated at the same event, held in his home state, Tabasco. "It's very important that we continue with this project." (Reporting by Abraham Gonzalez; Writing by Stefanie Eschenbacher; Editing by Peter Cooney)