Slim's telecoms group, America Movil (>> America Movil SAB de CV), agreed to back a 1 billion euro capital increase for Telekom Austria (>> Telekom Austria AG) and to pay 7.15 euros a share for the company's outstanding stock, in a co-ownership deal combining its stake with Austrian state holding company OIAG's holdings.

The price America Movil will pay per share represents a premium of 10.7 percent over the six-month average share price for Telekom Austria, which was the minimum bid America Movil and Austria would be obliged to make.

Latin America's biggest telecoms company already holds 26.4 percent of Telekom Austria. OIAG has 28.4 percent.

The agreement is a coup for America Movil, which is facing increasing regulation and competition in Latin America and which has suffered various setbacks in its attempts to expand in Europe. But the deal should allow Slim to begin consolidating his European ventures, which began in 2012, with investments of more than $1 billion (595 million pounds) in Telekom Austria and $3.4 billion in Dutch group KPN (>> KPN KON).

Wednesday's agreement envisages pooling the stake held by the OIAG with the stake held by America Movil in a syndicate in which both parties would have to vote in unison on major issues.

The syndicate agreement allows Slim, one of the world's richest people, to raise his holding in Telekom Austria. The OIAG has said its stake could fall to, but not below, 25 percent. It has declined to commit to keeping pace with Slim.

Slim's original purchase of his Telekom Austria and KPN stakes took advantage of market valuations seen as cheap at the time, as he sought diversification outside Latin America where regulators are looking askance at his dominance.

Telekom Austria was then battling fierce competition from three other operators in the country, but a consolidation of the market to three carriers was already in view and has subsequently eased the price rivalry somewhat.

Slim made an unsolicited offer for the rest of KPN last year and was rebuffed. He was keen to avoid a similar fate in Austria, where he courted politicians with promises to safeguard the Austrian headquarters and give the government veto rights.

Doubts about the agreement surfaced earlier on Wednesday, when labor representatives unhappy with the proposal boycotted a meeting designed to rubber-stamp the deal.

However, Austria's finance minister, Michael Spindelegger, said Telekom Austria would remain an Austrian company.

"The headquarters must remain in Vienna. This was already accepted by the negotiating partners," he said.

Telekom Austria shares closed down 3.19 percent at 6.65 euros before the agreement was sealed. America Movil shares closed up 0.47 percent at 12.90 pesos.

(Additional reporting by Dave Graham in Mexico City and Derek Brooks; Editing by David Goodman, Leslie Adler and Andre Grenon)

By Georgina Prodhan and Dave Graham

Stocks treated in this article : KPN KON, Telekom Austria AG, America Movil SAB de CV