Nov 16 (Reuters) - Spanish train maker Talgo said on Thursday an unidentified Hungarian business group made a preliminary offer to buy all its shares.

The group would offer to pay 5 euros ($5.42) per share, Talgo said in a filing to the stock market regulator, which represents a 28% premium over its closing share price on Wednesday, when its market value was 495 million euros ($537 million).

"As far as (Talgo) is aware, there is no decision from the investor in relation to the possible public offer of acquisition, nor is there any certainty that it will continue analysing the operation," Talgo CEO Gonzalo Urquijo said in the filing.

A company spokesperson said Talgo would not identify the potential buyer.

The regulator suspended trading in Talgo shares for one hour on Thursday morning.

Spanish news website Lainformacion had earlier reported that a Hungarian industrial group was considering buying Talgo.

Private equity fund Trilantic is Talgo's main shareholder.

($1 = 0.9220 euros) (Reporting by Joao Manuel Mauricio in Gdansk; editing by Inti Landauro and Jason Neely)