Mexican telecoms operator America Movil announced on Friday that it had launched a takeover bid for Dutch operator KPN, valuing the company at 10.2 billion euros ($13.6 billion).
America Movil, owned by tycoon Carlos Slim, already has a 29.77-percent stake in the Dutch telecoms company.
It has offered KPN 2.4 euros per share, the company said in a statement.
The price of shares in KPN leapt by slightly more than 18.0 percent in initial trading.
The Mexican operator launched the bid without waiting for the green light from KPN's management.
KPN's board of directors said it had "taken note"of the bid and would give the offer careful consideration while looking at all the options available.
America Movil last month ended an agreement not to increase its stake in KPN to more than 30 percent, after the Dutch operator said it was selling its German subsidiary.
KPN had annonced it was selling its German business E-Plus to Spain's Telefonica, a major competitor with America Movil in Latin America, for five billion euros ($6.6 billion).
The deal still needs the approval of shareholders, who are expected to meet in the next few weeks, and America Movil said it had not yet decided what it would do about the intended sale of E-Plus.
Slim is considered the world's second richest person after Microsoft founder Bill Gates, with an empire that includes telecommunications, mining, auto parts and retail.