Polish President Lech Kaczynski, who died Saturday in a plane crash in Russia, was a one-time anti-communist activist who teamed up with his twin brother to take his country in a nationalist, conservative direction.

Lech Kaczynski was elected president in 2005. (Markus Schreiber/Associated Press)

Kaczynski, 60, pursued a strongly pro-U.S. foreign policy, in accordance with a cross-party consensus that has grown in Poland since the fall of communism.

He was an enthusiastic backer of plans to build a U.S. missile defence facility in the country, the largest of the European Union's new eastern members.

The prickly nationalism of Kaczynski and his twin brother Jaroslaw — who served for part of 2006 as prime minister and is now opposition leader — sometimes complicated ties with European neighbours and Russia.

Lech Kaczynski long held out against the EU's so-called Lisbon reform treaty before signing it last November.

In the 1970s and 1980s, the Kaczynski brothers were activists in the anti-communist opposition and went on to serve as advisers to Solidarity founder Lech Walesa.

Kaczynski supported Walesa's presidential bid in 1990 and became the chief presidential adviser on security issues.

His co-operation with Walesa later ended in acrimony over political differences, and Walesa was defeated in 1995 by ex-communist Aleksander Kwasniewski.

Kaczynski served as Poland's justice minister in 2000-2001, and his tough stance against crime laid the foundations for the popularity that would fuel his later rise to the presidency.

He became mayor of Warsaw in 2001, and won respect for a no-nonsense style and plain-speaking reputation during his three years in office.

He became Poland's head of state in October 2005, and less than a year later, his identical twin became prime minister, leading some to refer to the country as the "twin republic."

Lech Kaczynski was killed along with his wife, Maria, an economist. He is survived by the couple's daughter, Marta; two granddaughters, Ewa and Martyna; his twin brother, Jaroslaw; and the twin's mother, Jadwiga.