Argentine oil group YPF has cut computer links with parent Repsol, two sources familiar with the matter said on Sunday, following Buenos Aires' plans unveiled last week to seize control of the leading energy company.

The move is the latest in a string of actions that have shut Spain's Repsol out of YPF, even before Argentina has implemented laws to provide the basis for the nationalization.

Last Monday, President Cristina Fernandez announced plans to expropriate a controlling 51 percent stake in YPF by seizing most of Repsol's shares, saying a failure of Repsol to invest sufficiently in YPF was contributing to an energy crunch in the country.

Repsol, which holds about 57 percent of YPF, said it had consistently raised investment at YPF and analysts said Argentina's price controls on oil and gas were the reason companies had not invested more in production.

Local media said that even before Fernandez finished her speech, the government's representative on YPF's board of directors, Roberto Baratta, had entered YPF's offices and read out the names of executives who would have to leave the premises immediately.

Hours after the expropriation was announced live on national television, the state-appointed interim administrator, Planning Minister Julio De Vido, occupied the company's offices in the upscale neighborhood of Puerto Madero.

The two sources said that days later, YPF shut down electronic communications with Repsol, preventing Repsol from accessing information about YPF's operations.

Later in the week the connection was cut between Repsol and YPF, one source said.

A spokesman for Planning Minister De Vido said he could not immediately confirm the cut-off. A spokesman for YPF could not immediately be reached to comment and Repsol declined comment.

New YPF directors have been appointed under the terms of a 30-day state intervention, which Fernandez decreed pending the expected congressional approval of the expropriation bill.

Senators are expected to vote on the bill on Wednesday, clearing the way for the lower house to vote on it within the next week or two - before the end of the interim state takeover. Fernandez controls Congress.

(Additional reporting by Helen Popper in Buenos Aires. Editing by Jane Barrett and Jane Merriman)