MADRID, Nov 30 (Reuters) - An experimental COVID-19 vaccine currently under development by Spanish pharmaceutical firm Hipra could be effective as a booster against variants of the virus, Spain's Science Minister Diana Morant said on Tuesday.

Morant said a Phase II trial on 1,000 volunteers who have already received another vaccine was producing good results on the alpha and beta variants of the coronavirus.

She told reporters after the weekly cabinet meeting that the vaccine would be a possible booster shot against variants.

"Hipra speaks of the ability of its vaccine to recombine variants, and that is one of the improvements that this vaccine presents compared to those that we have been inoculated with so far," she said.

"It is giving very good results precisely because it is a vaccine that recombines the proteins of the alpha and beta variants... delta came later and now we have the omicron."

Spain's medicines regulator two weeks ago authorised Hipra to carry out Phase II trials of its vaccine, which uses a recombinant protein like that of U.S. based drugmaker Novavax.

Before any eventual approval for use in humans, Hipra's vaccine candidate must demonstrate that it is safe and effective in the ongoing tests and at the final Phase III stage of clinical trials. (Reporting by Inti Landauro; Editing by Nathan Allen and Jan Harvey)